UI impl side painting default on

Turn on Impl Side Painting on Aura browser compositor by default
and add a disable compositor switch.

(Last attempt to re-land is at https://codereview.chromium.org/1160093005/, the try bot failure seem to be fixed with https://codereview.chromium.org/1166983007/ which is committed)

R=danakj
BUG=314185

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/962833003

Cr-Commit-Position: refs/heads/master@{#333656}

chrome/browser/chromeos/login/screenshot_testing/screenshot_testing_mixin.cc

@@ -27,7 +27,8 @@ void ScreenshotTestingMixin::SetUpInProcessBrowserTestFixture() {
 void ScreenshotTestingMixin::SetUpCommandLine(base::CommandLine* command_line) {
   if (enable_test_screenshots_) {
     command_line->AppendSwitch(switches::kEnablePixelOutputInTests);
-    command_line->AppendSwitch(switches::kUIEnableImplSidePainting);
+  } else {
+    command_line->AppendSwitch(switches::kUIDisableImplSidePainting);
   }
 }
 

ui/compositor/compositor_switches.cc

@@ -20,7 +20,7 @@ const char kUIDisableThreadedCompositing[] = "ui-disable-threaded-compositing";
 const char kUIEnableCompositorAnimationTimelines[] =
     "ui-enable-compositor-animation-timelines";
 
-const char kUIEnableImplSidePainting[] = "ui-enable-impl-side-painting";
+const char kUIDisableImplSidePainting[] = "ui-disable-impl-side-painting";
 
 const char kUIDisableSlimmingPaint[] = "ui-disable-slimming-paint";
 
@@ -35,7 +35,8 @@ namespace ui {
 bool IsUIImplSidePaintingEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
-  return command_line.HasSwitch(switches::kUIEnableImplSidePainting);
+
+  return !command_line.HasSwitch(switches::kUIDisableImplSidePainting);
 }
 
 bool IsUIZeroCopyEnabled() {

ui/compositor/compositor_switches.h

@@ -14,7 +14,7 @@ COMPOSITOR_EXPORT extern const char kEnablePixelOutputInTests[];
 COMPOSITOR_EXPORT extern const char kUIDisableSlimmingPaint[];
 COMPOSITOR_EXPORT extern const char kUIDisableThreadedCompositing[];
 COMPOSITOR_EXPORT extern const char kUIEnableCompositorAnimationTimelines[];
-COMPOSITOR_EXPORT extern const char kUIEnableImplSidePainting[];
+COMPOSITOR_EXPORT extern const char kUIDisableImplSidePainting[];
 COMPOSITOR_EXPORT extern const char kUIEnableZeroCopy[];
 COMPOSITOR_EXPORT extern const char kUIShowPaintRects[];