Add flag to disable impl-side painting

cc/switches.cc

Index: cc/switches.cc
diff --git a/cc/switches.cc b/cc/switches.cc
index 1352f3ae98fcf9a7eafc66f931448830ccbb2465..cbb83fae6b58e249c7ab4751fc639d4e05cf4853 100644
--- a/cc/switches.cc
+++ b/cc/switches.cc
@@ -17,6 +17,10 @@ const char kDisableThreadedAnimation[]      = "disable-threaded-animation";
 // Send a message for every frame from the impl thread to the parent compositor.
 const char kEnableCompositorFrameMessage[] = "enable-compositor-frame-message";
 
+// Paint content on the main thread instead of the compositor thread.
+// Overrides the kEnableImplSidePainting flag.
+const char kDisableImplSidePainting[] = "disable-impl-side-painting";
+
 // Paint content on the compositor thread instead of the main thread.
 const char kEnableImplSidePainting[] = "enable-impl-side-painting";
 
@@ -74,5 +78,20 @@ const char kSlowDownRasterScaleFactor[] = "slow-down-raster-scale-factor";
 // Schedule rasterization jobs according to their estimated processing cost.
 const char kUseCheapnessEstimator[] = "use-cheapness-estimator";
 
+bool IsImplSidePaintingEnabled() {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(cc::switches::kDisableImplSidePainting))
+    return false;
+  else if (command_line.HasSwitch(cc::switches::kEnableImplSidePainting))
+    return true;
+
+#if defined(OS_ANDROID)
+  return true;
+#else
+  return false;
+#endif
+}
+
 }  // namespace switches
 }  // namespace cc