diff --git a/src/Browser.js b/src/Browser.js
deleted file mode 100644
index 3aae1963d6674..0000000000000
--- a/src/Browser.js
+++ /dev/null
@@ -1,386 +0,0 @@
-/**
- * Copyright 2017 Google Inc. All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-const {helper, assert} = require('./helper');
-const {Target} = require('./Target');
-const EventEmitter = require('events');
-const {TaskQueue} = require('./TaskQueue');
-const {Events} = require('./Events');
-// Used as a TypeDef
-// eslint-disable-next-line no-unused-vars
-const {Connection} = require('./Connection');
-
-class Browser extends EventEmitter {
-  /**
-   * @param {!Connection} connection
-   * @param {!Array<string>} contextIds
-   * @param {boolean} ignoreHTTPSErrors
-   * @param {?Puppeteer.Viewport} defaultViewport
-   * @param {?Puppeteer.ChildProcess} process
-   * @param {function()=} closeCallback
-   */
-  static async create(connection, contextIds, ignoreHTTPSErrors, defaultViewport, process, closeCallback) {
-    const browser = new Browser(connection, contextIds, ignoreHTTPSErrors, defaultViewport, process, closeCallback);
-    await connection.send('Target.setDiscoverTargets', {discover: true});
-    return browser;
-  }
-
-  /**
-   * @param {!Connection} connection
-   * @param {!Array<string>} contextIds
-   * @param {boolean} ignoreHTTPSErrors
-   * @param {?Puppeteer.Viewport} defaultViewport
-   * @param {?Puppeteer.ChildProcess} process
-   * @param {(function():Promise)=} closeCallback
-   */
-  constructor(connection, contextIds, ignoreHTTPSErrors, defaultViewport, process, closeCallback) {
-    super();
-    this._ignoreHTTPSErrors = ignoreHTTPSErrors;
-    this._defaultViewport = defaultViewport;
-    this._process = process;
-    this._screenshotTaskQueue = new TaskQueue();
-    this._connection = connection;
-    this._closeCallback = closeCallback || new Function();
-
-    this._defaultContext = new BrowserContext(this._connection, this, null);
-    /** @type {Map<string, BrowserContext>} */
-    this._contexts = new Map();
-    for (const contextId of contextIds)
-      this._contexts.set(contextId, new BrowserContext(this._connection, this, contextId));
-
-    /** @type {Map<string, Target>} */
-    this._targets = new Map();
-    this._connection.on(Events.Connection.Disconnected, () => this.emit(Events.Browser.Disconnected));
-    this._connection.on('Target.targetCreated', this._targetCreated.bind(this));
-    this._connection.on('Target.targetDestroyed', this._targetDestroyed.bind(this));
-    this._connection.on('Target.targetInfoChanged', this._targetInfoChanged.bind(this));
-  }
-
-  /**
-   * @return {?Puppeteer.ChildProcess}
-   */
-  process() {
-    return this._process;
-  }
-
-  /**
-   * @return {!Promise<!BrowserContext>}
-   */
-  async createIncognitoBrowserContext() {
-    const {browserContextId} = await this._connection.send('Target.createBrowserContext');
-    const context = new BrowserContext(this._connection, this, browserContextId);
-    this._contexts.set(browserContextId, context);
-    return context;
-  }
-
-  /**
-   * @return {!Array<!BrowserContext>}
-   */
-  browserContexts() {
-    return [this._defaultContext, ...Array.from(this._contexts.values())];
-  }
-
-  /**
-   * @return {!BrowserContext}
-   */
-  defaultBrowserContext() {
-    return this._defaultContext;
-  }
-
-  /**
-   * @param {?string} contextId
-   */
-  async _disposeContext(contextId) {
-    await this._connection.send('Target.disposeBrowserContext', {browserContextId: contextId || undefined});
-    this._contexts.delete(contextId);
-  }
-
-  /**
-   * @param {!Protocol.Target.targetCreatedPayload} event
-   */
-  async _targetCreated(event) {
-    const targetInfo = event.targetInfo;
-    const {browserContextId} = targetInfo;
-    const context = (browserContextId && this._contexts.has(browserContextId)) ? this._contexts.get(browserContextId) : this._defaultContext;
-
-    const target = new Target(targetInfo, context, () => this._connection.createSession(targetInfo), this._ignoreHTTPSErrors, this._defaultViewport, this._screenshotTaskQueue);
-    assert(!this._targets.has(event.targetInfo.targetId), 'Target should not exist before targetCreated');
-    this._targets.set(event.targetInfo.targetId, target);
-
-    if (await target._initializedPromise) {
-      this.emit(Events.Browser.TargetCreated, target);
-      context.emit(Events.BrowserContext.TargetCreated, target);
-    }
-  }
-
-  /**
-   * @param {{targetId: string}} event
-   */
-  async _targetDestroyed(event) {
-    const target = this._targets.get(event.targetId);
-    target._initializedCallback(false);
-    this._targets.delete(event.targetId);
-    target._closedCallback();
-    if (await target._initializedPromise) {
-      this.emit(Events.Browser.TargetDestroyed, target);
-      target.browserContext().emit(Events.BrowserContext.TargetDestroyed, target);
-    }
-  }
-
-  /**
-   * @param {!Protocol.Target.targetInfoChangedPayload} event
-   */
-  _targetInfoChanged(event) {
-    const target = this._targets.get(event.targetInfo.targetId);
-    assert(target, 'target should exist before targetInfoChanged');
-    const previousURL = target.url();
-    const wasInitialized = target._isInitialized;
-    target._targetInfoChanged(event.targetInfo);
-    if (wasInitialized && previousURL !== target.url()) {
-      this.emit(Events.Browser.TargetChanged, target);
-      target.browserContext().emit(Events.BrowserContext.TargetChanged, target);
-    }
-  }
-
-  /**
-   * @return {string}
-   */
-  wsEndpoint() {
-    return this._connection.url();
-  }
-
-  /**
-   * @return {!Promise<!Puppeteer.Page>}
-   */
-  async newPage() {
-    return this._defaultContext.newPage();
-  }
-
-  /**
-   * @param {?string} contextId
-   * @return {!Promise<!Puppeteer.Page>}
-   */
-  async _createPageInContext(contextId) {
-    const {targetId} = await this._connection.send('Target.createTarget', {url: 'about:blank', browserContextId: contextId || undefined});
-    const target = await this._targets.get(targetId);
-    assert(await target._initializedPromise, 'Failed to create target for page');
-    const page = await target.page();
-    return page;
-  }
-
-  /**
-   * @return {!Array<!Target>}
-   */
-  targets() {
-    return Array.from(this._targets.values()).filter(target => target._isInitialized);
-  }
-
-  /**
-   * @return {!Target}
-   */
-  target() {
-    return this.targets().find(target => target.type() === 'browser');
-  }
-
-  /**
-   * @param {function(!Target):boolean} predicate
-   * @param {{timeout?: number}=} options
-   * @return {!Promise<!Target>}
-   */
-  async waitForTarget(predicate, options = {}) {
-    const {
-      timeout = 30000
-    } = options;
-    const existingTarget = this.targets().find(predicate);
-    if (existingTarget)
-      return existingTarget;
-    let resolve;
-    const targetPromise = new Promise(x => resolve = x);
-    this.on(Events.Browser.TargetCreated, check);
-    this.on(Events.Browser.TargetChanged, check);
-    try {
-      if (!timeout)
-        return await targetPromise;
-      return await helper.waitWithTimeout(targetPromise, 'target', timeout);
-    } finally {
-      this.removeListener(Events.Browser.TargetCreated, check);
-      this.removeListener(Events.Browser.TargetChanged, check);
-    }
-
-    /**
-     * @param {!Target} target
-     */
-    function check(target) {
-      if (predicate(target))
-        resolve(target);
-    }
-  }
-
-  /**
-   * @return {!Promise<!Array<!Puppeteer.Page>>}
-   */
-  async pages() {
-    const contextPages = await Promise.all(this.browserContexts().map(context => context.pages()));
-    // Flatten array.
-    return contextPages.reduce((acc, x) => acc.concat(x), []);
-  }
-
-  /**
-   * @return {!Promise<string>}
-   */
-  async version() {
-    const version = await this._getVersion();
-    return version.product;
-  }
-
-  /**
-   * @return {!Promise<string>}
-   */
-  async userAgent() {
-    const version = await this._getVersion();
-    return version.userAgent;
-  }
-
-  async close() {
-    await this._closeCallback.call(null);
-    this.disconnect();
-  }
-
-  disconnect() {
-    this._connection.dispose();
-  }
-
-  /**
-   * @return {boolean}
-   */
-  isConnected() {
-    return !this._connection._closed;
-  }
-
-  /**
-   * @return {!Promise<!Object>}
-   */
-  _getVersion() {
-    return this._connection.send('Browser.getVersion');
-  }
-}
-
-class BrowserContext extends EventEmitter {
-  /**
-   * @param {!Connection} connection
-   * @param {!Browser} browser
-   * @param {?string} contextId
-   */
-  constructor(connection, browser, contextId) {
-    super();
-    this._connection = connection;
-    this._browser = browser;
-    this._id = contextId;
-  }
-
-  /**
-   * @return {!Array<!Target>} target
-   */
-  targets() {
-    return this._browser.targets().filter(target => target.browserContext() === this);
-  }
-
-  /**
-   * @param {function(!Target):boolean} predicate
-   * @param {{timeout?: number}=} options
-   * @return {!Promise<!Target>}
-   */
-  waitForTarget(predicate, options) {
-    return this._browser.waitForTarget(target => target.browserContext() === this && predicate(target), options);
-  }
-
-  /**
-   * @return {!Promise<!Array<!Puppeteer.Page>>}
-   */
-  async pages() {
-    const pages = await Promise.all(
-        this.targets()
-            .filter(target => target.type() === 'page')
-            .map(target => target.page())
-    );
-    return pages.filter(page => !!page);
-  }
-
-  /**
-   * @return {boolean}
-   */
-  isIncognito() {
-    return !!this._id;
-  }
-
-  /**
-   * @param {string} origin
-   * @param {!Array<string>} permissions
-   */
-  async overridePermissions(origin, permissions) {
-    const webPermissionToProtocol = new Map([
-      ['geolocation', 'geolocation'],
-      ['midi', 'midi'],
-      ['notifications', 'notifications'],
-      ['push', 'push'],
-      ['camera', 'videoCapture'],
-      ['microphone', 'audioCapture'],
-      ['background-sync', 'backgroundSync'],
-      ['ambient-light-sensor', 'sensors'],
-      ['accelerometer', 'sensors'],
-      ['gyroscope', 'sensors'],
-      ['magnetometer', 'sensors'],
-      ['accessibility-events', 'accessibilityEvents'],
-      ['clipboard-read', 'clipboardReadWrite'],
-      ['clipboard-write', 'clipboardReadWrite'],
-      ['payment-handler', 'paymentHandler'],
-      // chrome-specific permissions we have.
-      ['midi-sysex', 'midiSysex'],
-    ]);
-    permissions = permissions.map(permission => {
-      const protocolPermission = webPermissionToProtocol.get(permission);
-      if (!protocolPermission)
-        throw new Error('Unknown permission: ' + permission);
-      return protocolPermission;
-    });
-    await this._connection.send('Browser.grantPermissions', {origin, browserContextId: this._id || undefined, permissions});
-  }
-
-  async clearPermissionOverrides() {
-    await this._connection.send('Browser.resetPermissions', {browserContextId: this._id || undefined});
-  }
-
-  /**
-   * @return {!Promise<!Puppeteer.Page>}
-   */
-  newPage() {
-    return this._browser._createPageInContext(this._id);
-  }
-
-  /**
-   * @return {!Browser}
-   */
-  browser() {
-    return this._browser;
-  }
-
-  async close() {
-    assert(this._id, 'Non-incognito profiles cannot be closed!');
-    await this._browser._disposeContext(this._id);
-  }
-}
-
-module.exports = {Browser, BrowserContext};
diff --git a/src/Browser.ts b/src/Browser.ts
new file mode 100644
index 0000000000000..b9aae8cd6ef23
--- /dev/null
+++ b/src/Browser.ts
@@ -0,0 +1,312 @@
+/**
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {helper, assert} from './helper';
+import {Target} from './Target';
+import * as EventEmitter from 'events';
+import {TaskQueue} from './TaskQueue';
+import {Events} from './Events';
+import {Connection} from './Connection';
+
+type BrowserCloseCallback = () => Promise<void> | void;
+
+/* TODO(jacktfranklin): once Target is migrated to TS
+ * we can import + use its type here. But right now Target
+ * is implemented in JS so we can't import the type and have to use
+ * Puppeteer.Target
+ */
+
+export class Browser extends EventEmitter {
+  static async create(connection: Connection, contextIds: string[], ignoreHTTPSErrors: boolean, defaultViewport?: Puppeteer.Viewport, process?: Puppeteer.ChildProcess, closeCallback?: BrowserCloseCallback): Promise<Browser> {
+    const browser = new Browser(connection, contextIds, ignoreHTTPSErrors, defaultViewport, process, closeCallback);
+    await connection.send('Target.setDiscoverTargets', {discover: true});
+    return browser;
+  }
+   _ignoreHTTPSErrors: boolean;
+   _defaultViewport?: Puppeteer.Viewport;
+   _process?: Puppeteer.ChildProcess;
+   _screenshotTaskQueue = new TaskQueue();
+   _connection: Connection;
+   _closeCallback: BrowserCloseCallback;
+   _defaultContext: BrowserContext;
+   _contexts: Map<string, BrowserContext>;
+   // TODO: once Target is in TypeScript we can type this properly.
+   _targets: Map<string, Puppeteer.Target>;
+
+   constructor(connection: Connection, contextIds: string[], ignoreHTTPSErrors: boolean, defaultViewport?: Puppeteer.Viewport, process?: Puppeteer.ChildProcess, closeCallback?: BrowserCloseCallback) {
+     super();
+     this._ignoreHTTPSErrors = ignoreHTTPSErrors;
+     this._defaultViewport = defaultViewport;
+     this._process = process;
+     this._screenshotTaskQueue = new TaskQueue();
+     this._connection = connection;
+     this._closeCallback = closeCallback || function(): void {};
+
+     this._defaultContext = new BrowserContext(this._connection, this, null);
+     this._contexts = new Map();
+     for (const contextId of contextIds)
+       this._contexts.set(contextId, new BrowserContext(this._connection, this, contextId));
+
+     this._targets = new Map();
+     this._connection.on(Events.Connection.Disconnected, () => this.emit(Events.Browser.Disconnected));
+     this._connection.on('Target.targetCreated', this._targetCreated.bind(this));
+     this._connection.on('Target.targetDestroyed', this._targetDestroyed.bind(this));
+     this._connection.on('Target.targetInfoChanged', this._targetInfoChanged.bind(this));
+   }
+
+   process(): Puppeteer.ChildProcess | null {
+     return this._process;
+   }
+
+   async createIncognitoBrowserContext(): Promise<BrowserContext> {
+     const {browserContextId} = await this._connection.send('Target.createBrowserContext');
+     const context = new BrowserContext(this._connection, this, browserContextId);
+     this._contexts.set(browserContextId, context);
+     return context;
+   }
+
+   browserContexts(): BrowserContext[] {
+     return [this._defaultContext, ...Array.from(this._contexts.values())];
+   }
+
+   defaultBrowserContext(): BrowserContext {
+     return this._defaultContext;
+   }
+
+   /**
+   * @param {?string} contextId
+   */
+   async _disposeContext(contextId?: string): Promise<void> {
+     await this._connection.send('Target.disposeBrowserContext', {browserContextId: contextId || undefined});
+     this._contexts.delete(contextId);
+   }
+
+   async _targetCreated(event: Protocol.Target.targetCreatedPayload): Promise<void> {
+     const targetInfo = event.targetInfo;
+     const {browserContextId} = targetInfo;
+     const context = (browserContextId && this._contexts.has(browserContextId)) ? this._contexts.get(browserContextId) : this._defaultContext;
+
+     const target = new Target(targetInfo, context, () => this._connection.createSession(targetInfo), this._ignoreHTTPSErrors, this._defaultViewport, this._screenshotTaskQueue);
+     assert(!this._targets.has(event.targetInfo.targetId), 'Target should not exist before targetCreated');
+     this._targets.set(event.targetInfo.targetId, target);
+
+     if (await target._initializedPromise) {
+       this.emit(Events.Browser.TargetCreated, target);
+       context.emit(Events.BrowserContext.TargetCreated, target);
+     }
+   }
+
+   /**
+   * @param {{targetId: string}} event
+   */
+   async _targetDestroyed(event: { targetId: string}): Promise<void> {
+     const target = this._targets.get(event.targetId);
+     target._initializedCallback(false);
+     this._targets.delete(event.targetId);
+     target._closedCallback();
+     if (await target._initializedPromise) {
+       this.emit(Events.Browser.TargetDestroyed, target);
+       target.browserContext().emit(Events.BrowserContext.TargetDestroyed, target);
+     }
+   }
+
+   /**
+   * @param {!Protocol.Target.targetInfoChangedPayload} event
+   */
+   _targetInfoChanged(event: Protocol.Target.targetInfoChangedPayload): void {
+     const target = this._targets.get(event.targetInfo.targetId);
+     assert(target, 'target should exist before targetInfoChanged');
+     const previousURL = target.url();
+     const wasInitialized = target._isInitialized;
+     target._targetInfoChanged(event.targetInfo);
+     if (wasInitialized && previousURL !== target.url()) {
+       this.emit(Events.Browser.TargetChanged, target);
+       target.browserContext().emit(Events.BrowserContext.TargetChanged, target);
+     }
+   }
+
+   wsEndpoint(): string {
+     return this._connection.url();
+   }
+
+   async newPage(): Promise<Puppeteer.Page> {
+     return this._defaultContext.newPage();
+   }
+
+   async _createPageInContext(contextId?: string): Promise<Puppeteer.Page> {
+     const {targetId} = await this._connection.send('Target.createTarget', {url: 'about:blank', browserContextId: contextId || undefined});
+     const target = await this._targets.get(targetId);
+     assert(await target._initializedPromise, 'Failed to create target for page');
+     const page = await target.page();
+     return page;
+   }
+
+   targets(): Puppeteer.Target[] {
+     return Array.from(this._targets.values()).filter(target => target._isInitialized);
+   }
+
+   target(): Puppeteer.Target {
+     return this.targets().find(target => target.type() === 'browser');
+   }
+
+   /**
+   * @param {function(!Target):boolean} predicate
+   * @param {{timeout?: number}=} options
+   * @return {!Promise<!Target>}
+   */
+   async waitForTarget(predicate: (x: Puppeteer.Target) => boolean, options: { timeout?: number} = {}): Promise<Puppeteer.Target> {
+     const {
+       timeout = 30000
+     } = options;
+     const existingTarget = this.targets().find(predicate);
+     if (existingTarget)
+       return existingTarget;
+     let resolve;
+     const targetPromise = new Promise<Puppeteer.Target>(x => resolve = x);
+     this.on(Events.Browser.TargetCreated, check);
+     this.on(Events.Browser.TargetChanged, check);
+     try {
+       if (!timeout)
+         return await targetPromise;
+       return await helper.waitWithTimeout<Puppeteer.Target>(targetPromise, 'target', timeout);
+     } finally {
+       this.removeListener(Events.Browser.TargetCreated, check);
+       this.removeListener(Events.Browser.TargetChanged, check);
+     }
+
+     function check(target: Puppeteer.Target): void  {
+       if (predicate(target))
+         resolve(target);
+     }
+   }
+
+   /**
+   * @return {!Promise<!Array<!Puppeteer.Page>>}
+   */
+   async pages(): Promise<Puppeteer.Page[]> {
+     const contextPages = await Promise.all(this.browserContexts().map(context => context.pages()));
+     // Flatten array.
+     return contextPages.reduce((acc, x) => acc.concat(x), []);
+   }
+
+   async version(): Promise<string> {
+     const version = await this._getVersion();
+     return version.product;
+   }
+
+   async userAgent(): Promise<string> {
+     const version = await this._getVersion();
+     return version.userAgent;
+   }
+
+   async close(): Promise<void> {
+     await this._closeCallback.call(null);
+     this.disconnect();
+   }
+
+   disconnect(): void {
+     this._connection.dispose();
+   }
+
+   isConnected(): boolean {
+     return !this._connection._closed;
+   }
+
+   _getVersion(): Promise<Protocol.Browser.getVersionReturnValue> {
+     return this._connection.send('Browser.getVersion');
+   }
+}
+
+export class BrowserContext extends EventEmitter {
+  _connection: Connection;
+  _browser: Browser;
+  _id?: string;
+
+  constructor(connection: Connection, browser: Browser, contextId?: string) {
+    super();
+    this._connection = connection;
+    this._browser = browser;
+    this._id = contextId;
+  }
+
+  targets(): Puppeteer.Target[] {
+    return this._browser.targets().filter(target => target.browserContext() === this);
+  }
+
+  waitForTarget(predicate: (x: Puppeteer.Target) => boolean, options: { timeout?: number}): Promise<Puppeteer.Target> {
+    return this._browser.waitForTarget(target => target.browserContext() === this && predicate(target), options);
+  }
+
+  async pages(): Promise<Puppeteer.Page[]> {
+    const pages = await Promise.all(
+        this.targets()
+            .filter(target => target.type() === 'page')
+            .map(target => target.page())
+    );
+    return pages.filter(page => !!page);
+  }
+
+  isIncognito(): boolean {
+    return !!this._id;
+  }
+
+  async overridePermissions(origin: string, permissions: Protocol.Browser.PermissionType[]): Promise<void> {
+    const webPermissionToProtocol = new Map<string, Protocol.Browser.PermissionType>([
+      ['geolocation', 'geolocation'],
+      ['midi', 'midi'],
+      ['notifications', 'notifications'],
+      // TODO: push isn't a valid type?
+      // ['push', 'push'],
+      ['camera', 'videoCapture'],
+      ['microphone', 'audioCapture'],
+      ['background-sync', 'backgroundSync'],
+      ['ambient-light-sensor', 'sensors'],
+      ['accelerometer', 'sensors'],
+      ['gyroscope', 'sensors'],
+      ['magnetometer', 'sensors'],
+      ['accessibility-events', 'accessibilityEvents'],
+      ['clipboard-read', 'clipboardReadWrite'],
+      ['clipboard-write', 'clipboardReadWrite'],
+      ['payment-handler', 'paymentHandler'],
+      // chrome-specific permissions we have.
+      ['midi-sysex', 'midiSysex'],
+    ]);
+    permissions = permissions.map(permission => {
+      const protocolPermission = webPermissionToProtocol.get(permission);
+      if (!protocolPermission)
+        throw new Error('Unknown permission: ' + permission);
+      return protocolPermission;
+    });
+    await this._connection.send('Browser.grantPermissions', {origin, browserContextId: this._id || undefined, permissions});
+  }
+
+  async clearPermissionOverrides(): Promise<void> {
+    await this._connection.send('Browser.resetPermissions', {browserContextId: this._id || undefined});
+  }
+
+  newPage(): Promise<Puppeteer.Page> {
+    return this._browser._createPageInContext(this._id);
+  }
+
+  browser(): Browser {
+    return this._browser;
+  }
+
+  async close(): Promise<void> {
+    assert(this._id, 'Non-incognito profiles cannot be closed!');
+    await this._browser._disposeContext(this._id);
+  }
+}
diff --git a/src/Connection.ts b/src/Connection.ts
index 04329d1336b0d..f6bc2e4e02010 100644
--- a/src/Connection.ts
+++ b/src/Connection.ts
@@ -72,7 +72,7 @@ export class Connection extends EventEmitter {
     return this._url;
   }
 
-  send<ReturnType extends {}>(method: string, params = {}): Promise<ReturnType> {
+  send<T extends keyof Protocol.CommandParameters>(method: T, params?: Protocol.CommandParameters[T]): Promise<Protocol.CommandReturnValues[T]> {
     const id = this._rawSend({method, params});
     return new Promise((resolve, reject) => {
       this._callbacks.set(id, {resolve, reject, error: new Error(), method});
@@ -147,7 +147,7 @@ export class Connection extends EventEmitter {
    * @return {!Promise<!CDPSession>}
    */
   async createSession(targetInfo: Protocol.Target.TargetInfo): Promise<CDPSession> {
-    const {sessionId} = await this.send<Protocol.Target.attachedToTargetPayload>('Target.attachToTarget', {targetId: targetInfo.targetId, flatten: true});
+    const {sessionId} = await this.send('Target.attachToTarget', {targetId: targetInfo.targetId, flatten: true});
     return this._sessions.get(sessionId);
   }
 }
diff --git a/src/Page.js b/src/Page.js
index f1382a5b3d7d3..71bde110198a0 100644
--- a/src/Page.js
+++ b/src/Page.js
@@ -31,6 +31,9 @@ const {Coverage} = require('./Coverage');
 const {Worker: PuppeteerWorker} = require('./Worker');
 // Import used as typedef
 // eslint-disable-next-line no-unused-vars
+const {Browser, BrowserContext} = require('./Browser');
+// Import used as typedef
+// eslint-disable-next-line no-unused-vars
 const {createJSHandle, JSHandle, ElementHandle} = require('./JSHandle');
 const {Accessibility} = require('./Accessibility');
 const {TimeoutSettings} = require('./TimeoutSettings');
@@ -204,14 +207,14 @@ class Page extends EventEmitter {
   }
 
   /**
-   * @return {!Puppeteer.Browser}
+   * @return {!Browser}
    */
   browser() {
     return this._target.browser();
   }
 
   /**
-   * @return {!Puppeteer.BrowserContext}
+   * @return {!BrowserContext}
    */
   browserContext() {
     return this._target.browserContext();
diff --git a/src/Puppeteer.js b/src/Puppeteer.js
index f8b6f81509b90..8f84cacfc5999 100644
--- a/src/Puppeteer.js
+++ b/src/Puppeteer.js
@@ -17,6 +17,9 @@ const Launcher = require('./Launcher');
 const {BrowserFetcher} = require('./BrowserFetcher');
 const Errors = require('./Errors');
 const DeviceDescriptors = require('./DeviceDescriptors');
+// Import used as typedef
+// eslint-disable-next-line no-unused-vars
+const {Browser} = require('./Browser');
 
 module.exports = class {
   /**
@@ -35,7 +38,7 @@ module.exports = class {
 
   /**
    * @param {!(Launcher.LaunchOptions & Launcher.ChromeArgOptions & Launcher.BrowserOptions & {product?: string, extraPrefsFirefox?: !object})=} options
-   * @return {!Promise<!Puppeteer.Browser>}
+   * @return {!Promise<!Browser>}
    */
   launch(options = {}) {
     if (options.product)
@@ -45,7 +48,7 @@ module.exports = class {
 
   /**
    * @param {!(Launcher.BrowserOptions & {browserWSEndpoint?: string, browserURL?: string, transport?: !Puppeteer.ConnectionTransport}) & {product?: string}=} options
-   * @return {!Promise<!Puppeteer.Browser>}
+   * @return {!Promise<!Browser>}
    */
   connect(options) {
     if (options.product)
diff --git a/src/Target.js b/src/Target.js
index 54825c2c5aca4..ad3a98dceb957 100644
--- a/src/Target.js
+++ b/src/Target.js
@@ -24,11 +24,14 @@ const {CDPSession} = require('./Connection');
 // understand that unfortunately.
 // eslint-disable-next-line no-unused-vars
 const {TaskQueue} = require('./TaskQueue');
+// Import used as typedef
+// eslint-disable-next-line no-unused-vars
+const {Browser, BrowserContext} = require('./Browser');
 
 class Target {
   /**
    * @param {!Protocol.Target.TargetInfo} targetInfo
-   * @param {!Puppeteer.BrowserContext} browserContext
+   * @param {!BrowserContext} browserContext
    * @param {!function():!Promise<!CDPSession>} sessionFactory
    * @param {boolean} ignoreHTTPSErrors
    * @param {?Puppeteer.Viewport} defaultViewport
@@ -115,14 +118,14 @@ class Target {
   }
 
   /**
-   * @return {!Puppeteer.Browser}
+   * @return {!Browser}
    */
   browser() {
     return this._browserContext.browser();
   }
 
   /**
-   * @return {!Puppeteer.BrowserContext}
+   * @return {!BrowserContext}
    */
   browserContext() {
     return this._browserContext;
diff --git a/src/TaskQueue.ts b/src/TaskQueue.ts
index d459d0550f5b5..e3b8f1549ca9d 100644
--- a/src/TaskQueue.ts
+++ b/src/TaskQueue.ts
@@ -19,7 +19,7 @@
  * to make this into TaskQueue<T> and let the caller tell us what types
  * the promise in the queue should return.
  */
-class TaskQueue {
+export class TaskQueue {
   _chain: Promise<void | any>;
 
   constructor() {
@@ -32,5 +32,3 @@ class TaskQueue {
     return result;
   }
 }
-
-export = {TaskQueue};
diff --git a/src/externs.d.ts b/src/externs.d.ts
index 0fa4f3c515eea..171fa23ffff85 100644
--- a/src/externs.d.ts
+++ b/src/externs.d.ts
@@ -1,4 +1,3 @@
-import { Browser as RealBrowser, BrowserContext as RealBrowserContext} from './Browser.js';
 import {Target as RealTarget} from './Target.js';
 import {Page as RealPage} from './Page.js';
 import {Frame as RealFrame, FrameManager as RealFrameManager}  from './FrameManager.js';
@@ -7,8 +6,6 @@ import { NetworkManager as RealNetworkManager, Request as RealRequest, Response
 import * as child_process from 'child_process';
 declare global {
   module Puppeteer {
-    export class Browser extends RealBrowser {}
-    export class BrowserContext extends RealBrowserContext {}
     export class Target extends RealTarget {}
     export class Frame extends RealFrame {}
     export class FrameManager extends RealFrameManager {}
diff --git a/test/oopif.spec.js b/test/oopif.spec.js
index cc048c9540e7c..7ce0c3a12e1c9 100644
--- a/test/oopif.spec.js
+++ b/test/oopif.spec.js
@@ -64,7 +64,7 @@ describeChromeOnly('OOPIF', function() {
 
 
 /**
- * @param {!Puppeteer.BrowserContext} context
+ * @param {!BrowserContext} context
  */
 function oopifs(context) {
   return context.targets().filter(target => target._targetInfo.type === 'iframe');
diff --git a/utils/doclint/check_public_api/index.js b/utils/doclint/check_public_api/index.js
index ef1de7c4557e4..958f9a59c88ab 100644
--- a/utils/doclint/check_public_api/index.js
+++ b/utils/doclint/check_public_api/index.js
@@ -335,6 +335,10 @@ function compareDocumentations(actual, expected) {
         actualName: '"load"|"domcontentloaded"|"networkidle0"|"networkidle2"|Array',
         expectedName: '"load"|"domcontentloaded"|"networkidle0"|"networkidle2"|Array<PuppeteerLifeCycleEvent>'
       }],
+      ['Method BrowserContext.overridePermissions() permissions', {
+        actualName: 'Array<string>',
+        expectedName: 'Array<PermissionType>'
+      }],
     ]);
 
     const expectedForSource = expectedNamingMismatches.get(source);