Implements core logic for Pixel Canvas

ui/compositor/compositor_switches.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/compositor_switches.h"
 
 #include "base/command_line.h"
 
 namespace switches {
 
@@ skipping 10 matching lines @@
 const char kUIDisablePartialSwap[] = "ui-disable-partial-swap";
 
 const char kUIEnableRGBA4444Textures[] = "ui-enable-rgba-4444-textures";
 
 const char kUIEnableZeroCopy[] = "ui-enable-zero-copy";
 
 const char kUIShowPaintRects[] = "ui-show-paint-rects";
 
 const char kUISlowAnimations[] = "ui-slow-animations";
 
+// If enabled, all draw commnads recorded on canvas are done in pixel aligned
+// measurements. This also enables scaling of all elements in views and layers
+// to be done via corner points. See go/pixel-canvas

[vmpstr, 2017/07/11 17:37:21]

can you use a public link shortener (like goo.gl) for the doc link, since it
should be accessible externally.

[malaykeshav, 2017/07/12 00:55:35]

Done

+const char kEnablePixelCanvasRecording[] = "enable-pixel-canvas-recording";
+
 }  // namespace switches
 
 namespace ui {
+namespace {
+bool kEnablePixelCanvasForTesting = false;
+}
 
 bool IsUIZeroCopyEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   return command_line.HasSwitch(switches::kUIEnableZeroCopy);
 }
 
+bool IsPixelCanvasRecordingEnabled() {
+  static const bool kIsPixelCanvasRecordingEnabled =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnablePixelCanvasRecording);
+  return kIsPixelCanvasRecordingEnabled || kEnablePixelCanvasForTesting;
+}
+
+void SetPixelCanvasForTesting(bool value) {

[vmpstr, 2017/07/11 17:37:21]

I think this function should be called EnablePixelCanvasForTesting or something
like that, since it can't really disable the pixel canvas if one is set. Or are
you relying on the fact that it's off by default?

[malaykeshav, 2017/07/12 00:55:35]

During unittests, the switch is disabled, so kIsPixelCanvasRecordingEnabled is
always set to false. kEnablePixelCanvasForTesting becomes the only way to enable
or disable PixelCanvas.

+  kEnablePixelCanvasForTesting = value;
+}
+
 }  // namespace ui