feat: add cumulativeCPUUsage to AppMetrics and CPUUsage

This allows apps to measure their CPU usage over any given period
without worrying about other calls affecting the output,
as they would with `percentCPUUsage`.

docs/api/structures/cpu-usage.md

@@ -2,6 +2,7 @@
 
 * `percentCPUUsage` number - Percentage of CPU used since the last call to getCPUUsage.
   First call returns 0.
+* `cumulativeCPUUsage` number - Total seconds of CPU time used since process startup.
 * `idleWakeupsPerSecond` number - The number of average idle CPU wakeups per second
   since the last call to getCPUUsage. First call returns 0. Will always return 0 on
   Windows.

shell/browser/api/electron_api_app.cc

@@ -1280,6 +1280,7 @@ std::vector<gin_helper::Dictionary> App::GetAppMetrics(v8::Isolate* isolate) {
     std::optional<double> usage =
         process_metric.second->metrics->GetPlatformIndependentCPUUsage();
     cpu_dict.Set("percentCPUUsage", usage.value_or(0) / processor_count);
+    cpu_dict.Set("cumulativeCPUUsage", process_metric.second->metrics->GetCumulativeCPUUsage().InSecondsF());
 
 #if !BUILDFLAG(IS_WIN)
     cpu_dict.Set("idleWakeupsPerSecond",

shell/common/api/electron_bindings.cc

@@ -280,6 +280,8 @@ v8::Local<v8::Value> ElectronBindings::GetCPUUsage(
   std::optional<double> usage = metrics->GetPlatformIndependentCPUUsage();
   dict.Set("percentCPUUsage", usage.value_or(0) / processor_count);
 
+  dict.Set("cumulativeCPUUsage", metrics->GetCumulativeCPUUsage().InSecondsF());
+
   // NB: This will throw NOTIMPLEMENTED() on Windows
   // For backwards compatibility, we'll return 0
 #if !BUILDFLAG(IS_WIN)

spec/api-app-spec.ts

@@ -1442,6 +1442,7 @@ describe('app module', () => {
 
         types.push(entry.type);
         expect(entry.cpu).to.have.ownProperty('percentCPUUsage').that.is.a('number');
+        expect(entry.cpu).to.have.ownProperty('cumulativeCPUUsage').that.is.a('number');
         expect(entry.cpu).to.have.ownProperty('idleWakeupsPerSecond').that.is.a('number');
 
         expect(entry.memory).to.have.property('workingSetSize').that.is.greaterThan(0);

spec/api-process-spec.ts

@@ -26,6 +26,7 @@ describe('process module', () => {
       it('returns a cpu usage object', async () => {
         const cpuUsage = await w.webContents.executeJavaScript('process.getCPUUsage()');
         expect(cpuUsage.percentCPUUsage).to.be.a('number');
+        expect(cpuUsage.cumulativeCPUUsage).to.be.a('number');
         expect(cpuUsage.idleWakeupsPerSecond).to.be.a('number');
       });
     });
@@ -124,6 +125,7 @@ describe('process module', () => {
       it('returns a cpu usage object', () => {
         const cpuUsage = process.getCPUUsage();
         expect(cpuUsage.percentCPUUsage).to.be.a('number');
+        expect(cpuUsage.cumulativeCPUUsage).to.be.a('number');
         expect(cpuUsage.idleWakeupsPerSecond).to.be.a('number');
       });
     });