Add a flag to enable remote CoreAnimation API.

ui/base/cocoa/remote_layer_api.mm

Index: ui/base/cocoa/remote_layer_api.mm
diff --git a/ui/base/cocoa/remote_layer_api.mm b/ui/base/cocoa/remote_layer_api.mm
index c58402ffe9ae3e84d0d3a4134c739f39810d1840..1bf64b46cfb1c3024e95e9b32614e0b1860ad7bc 100644
--- a/ui/base/cocoa/remote_layer_api.mm
+++ b/ui/base/cocoa/remote_layer_api.mm
@@ -4,11 +4,20 @@
 
 #include "ui/base/cocoa/remote_layer_api.h"
 
+#include "base/command_line.h"
+#include "ui/base/ui_base_switches.h"
+
 #include <objc/runtime.h>
 
 namespace ui {
 
 bool RemoteLayerAPISupported() {
+  static bool enabled_at_command_line =

[sky, 2014/08/14 00:19:08]

Unless there is really a reason to make this static I wouldn't. Otherwise unit
tests may be tricky.

[ccameron, 2014/08/14 00:33:31]

Done.

+      CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableRemoteCoreAnimation);
+  if (!enabled_at_command_line)
+    return false;
+
   // Verify the GPU process interfaces are present.
   static Class caContextClass = NSClassFromString(@"CAContext");
   if (!caContextClass)