cc: Implement overdraw feedback debugging feature.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index df6710779c7e8612115e41d4f6acc1c534414745..e7fdd232900a5c774613d268f66f99fd6a101c19 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -733,6 +733,9 @@ const FeatureEntry kFeatureEntries[] = {
      IDS_FLAGS_GL_COMPOSITED_TEXTURE_QUAD_BORDERS,
      IDS_FLAGS_GL_COMPOSITED_TEXTURE_QUAD_BORDERS_DESCRIPTION, kOsAll,
      SINGLE_VALUE_TYPE(cc::switches::kGlCompositedTextureQuadBorder)},
+    {"show-overdraw-feedback", IDS_FLAGS_SHOW_OVERDRAW_FEEDBACK,
+     IDS_FLAGS_SHOW_OVERDRAW_FEEDBACK_DESCRIPTION, kOsAll,
+     SINGLE_VALUE_TYPE(cc::switches::kShowOverdrawFeedback)},
 #if BUILDFLAG(ENABLE_WEBRTC)
     {"disable-webrtc-hw-decoding", IDS_FLAGS_WEBRTC_HW_DECODING_NAME,
      IDS_FLAGS_WEBRTC_HW_DECODING_DESCRIPTION, kOsAndroid | kOsCrOS,
@@ -1049,6 +1052,10 @@ const FeatureEntry kFeatureEntries[] = {
      IDS_FLAGS_UI_SLOW_ANIMATIONS_NAME,
      IDS_FLAGS_UI_SLOW_ANIMATIONS_DESCRIPTION, kOsCrOS,
      SINGLE_VALUE_TYPE(switches::kUISlowAnimations)},
+    {"ui-disable-partial-swap",
+     IDS_FLAGS_UI_PARTIAL_SWAP_NAME,
+     IDS_FLAGS_UI_PARTIAL_SWAP_DESCRIPTION, kOsCrOS,

[danakj, 2017/01/16 18:17:55]

Why is this chromeos only, the flag works anywhere. Could be useful for software
compositing on linux and such for example too?

But then also.. why is it in this CL? Do you need to use this when showing
overdraw?

[reveman, 2017/01/16 22:46:18]

Made it available on all platforms in latest patch.
This is useful when debugging overdraw. Overdraw feedback works correctly with
partial updates and sometimes that's useful for debugging but it often results
in harder to understand output as you're not seeing the overdraw result for the
complete screen at the current compositor state. E.g. if you move a window and
that makes the compositor decide to use a new approach for occlusion culling
then only the partially updated area of the screen will show overdraw feedback
that match that new approach while the rest will show the correct overdraw for
the old approach. I'll be explaining this in how-to going up on chromium.org.

+     SINGLE_DISABLE_VALUE_TYPE(switches::kUIDisablePartialSwap)},
     {"disable-cloud-import", IDS_FLAGS_CLOUD_IMPORT,
      IDS_FLAGS_CLOUD_IMPORT_DESCRIPTION, kOsCrOS,
      SINGLE_DISABLE_VALUE_TYPE(chromeos::switches::kDisableCloudImport)},