fix: restore ability to disable color correct rendering

In Electron 2.0, `--disable-features=ColorCorrectRendering` could be
used to make the app use the display color space (e.g. P3 on Macs)
instead of color correcting to sRGB. Because color correct rendering is
always enabled on Chromium 62 and later and because
`--force-color-profile` has no effect on macOS, apps that need e.g. P3
colors are currently stuck on Electron 2.0.

This restores the functionality removed in
https://chromium-review.googlesource.com/698347 in the form of the
`--disable-color-correct-rendering` switch.

This can be removed once web content (including WebGL) learn how
to deal with color spaces. That is being tracked at
https://crbug.com/634542 and https://crbug.com/711107.

As an example of a widely used app using
`--disable-features=ColorCorrectRendering`, see VSCode:
https://github.com/Microsoft/vscode/blob/3f33ef2593d3efe6eca5230f3d34d3406fb73498/src/main.js#L138-L139

Notes: Add `--disable-color-correct-rendering` switch

patches/common/chromium/.patches

@@ -77,3 +77,4 @@ content_allow_embedder_to_prevent_locking_scheme_registry.patch
 fix_trackpad_scrolling.patch
 mac_fix_form_control_rendering_on_10_14_mojave.patch
 ensure_cookie_store.patch
+disable_color_correct_rendering.patch

patches/common/chromium/disable_color_correct_rendering.patch

@@ -0,0 +1,95 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Birunthan Mohanathas <birunthan@mohanathas.com>
+Date: Thu, 29 Nov 2018 20:53:52 +0200
+Subject: Add --disable-color-correct-rendering switch
+
+This allows apps to use the display color space (e.g. P3 on Macs)
+instead of sRGB. This effectively restores the functionality removed
+in: https://chromium-review.googlesource.com/698347
+
+This can be removed once web content (including WebGL) learn how
+to deal with color spaces. That is being tracked at
+https://crbug.com/634542 and https://crbug.com/711107.
+
+diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
+index 507ece40522fc29a56908d9a6532947a7f67db35..1659c05bfeecbf8ef4264f946aa045d58beb2775 100644
+--- a/cc/trees/layer_tree_host_impl.cc
++++ b/cc/trees/layer_tree_host_impl.cc
+@@ -1578,6 +1578,10 @@ void LayerTreeHostImpl::SetIsLikelyToRequireADraw(
+ }
+
+ RasterColorSpace LayerTreeHostImpl::GetRasterColorSpace() const {
++  if (!settings_.enable_color_correct_rendering) {
++    return {};
++  }
++
+   RasterColorSpace result;
+   // The pending tree will have the most recently updated color space, so
+   // prefer that.
+diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
+index 736df815a2815484b561bdc4828dbb8592a43d3a..b9b624e475bc244154febb214d88c63aaba5bbab 100644
+--- a/cc/trees/layer_tree_settings.h
++++ b/cc/trees/layer_tree_settings.h
+@@ -98,6 +98,8 @@ class CC_EXPORT LayerTreeSettings {
+
+   bool enable_mask_tiling = true;
+
++  bool enable_color_correct_rendering = true;
++
+   // If set to true, the compositor may selectively defer image decodes to the
+   // Image Decode Service and raster tiles without images until the decode is
+   // ready.
+diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
+index bdecceea7e66605869548efc15181d88cfb8a438..0f0e20308b8a7753ee40e12f8da9bbf0de4aef70 100644
+--- a/content/browser/gpu/gpu_process_host.cc
++++ b/content/browser/gpu/gpu_process_host.cc
+@@ -192,6 +192,7 @@ GpuTerminationStatus ConvertToGpuTerminationStatus(
+
+ // Command-line switches to propagate to the GPU process.
+ static const char* const kSwitchNames[] = {
++    "disable-color-correct-rendering",
+     service_manager::switches::kDisableSeccompFilterSandbox,
+     service_manager::switches::kGpuSandboxAllowSysVShm,
+     service_manager::switches::kGpuSandboxFailuresFatal,
+diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
+index 05e0ee79e5ada8eee03b2bff9c127b4f11610c17..b19d8e8c53db0396b39fed0e2e530705c5337284 100644
+--- a/content/browser/renderer_host/render_process_host_impl.cc
++++ b/content/browser/renderer_host/render_process_host_impl.cc
+@@ -2779,6 +2779,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
+   // Propagate the following switches to the renderer command line (along
+   // with any associated values) if present in the browser command line.
+   static const char* const kSwitchNames[] = {
++    "disable-color-correct-rendering",
+     network::switches::kNoReferrers,
+     service_manager::switches::kDisableInProcessStackTraces,
+     service_manager::switches::kDisableSeccompFilterSandbox,
+diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
+index 560c7caaa74c295a203bfa53c1acc63f1eb4283f..39fe8a6696d2cf0201d9b04364ffabab7af50bca 100644
+--- a/content/renderer/render_widget.cc
++++ b/content/renderer/render_widget.cc
+@@ -2458,6 +2458,9 @@ cc::LayerTreeSettings RenderWidget::GenerateLayerTreeSettings(
+   settings.main_frame_before_activation_enabled =
+       cmd.HasSwitch(cc::switches::kEnableMainFrameBeforeActivation);
+
++  settings.enable_color_correct_rendering =
++    !cmd.HasSwitch("disable-color-correct-rendering");
++
+   // Checkerimaging is not supported for synchronous single-threaded mode, which
+   // is what the renderer uses if its not threaded.
+   settings.enable_checker_imaging =
+diff --git a/ui/gfx/mac/io_surface.cc b/ui/gfx/mac/io_surface.cc
+index 00ad38db090096645d9ef9e3220a48661b6401df..57c9b06756efc0179ed9145cd14068ef53f228a8 100644
+--- a/ui/gfx/mac/io_surface.cc
++++ b/ui/gfx/mac/io_surface.cc
+@@ -199,6 +199,11 @@ IOSurfaceRef CreateIOSurface(const gfx::Size& size,
+
+   // Ensure that all IOSurfaces start as sRGB.
+   CGColorSpaceRef color_space = base::mac::GetSRGBColorSpace();
++  auto* cmd_line = base::CommandLine::ForCurrentProcess();
++  if (cmd_line->HasSwitch("disable-color-correct-rendering")) {
++    color_space = base::mac::GetSystemColorSpace();
++  }
++
+   base::ScopedCFTypeRef<CFDataRef> color_space_icc(
+       CGColorSpaceCopyICCProfile(color_space));
+   IOSurfaceSetValue(surface, CFSTR("IOSurfaceColorSpace"), color_space_icc);