Makes tests either use mock compositor or mock WebGraphicsContext3D

chrome/browser/chrome_browser_main_extra_parts_aura.cc

Index: chrome/browser/chrome_browser_main_extra_parts_aura.cc
diff --git a/chrome/browser/chrome_browser_main_extra_parts_aura.cc b/chrome/browser/chrome_browser_main_extra_parts_aura.cc
index 0ce66bdd945add6f9d028045f8d1612c2267fcf9..a074ad7e04d27d0b8ea56066b99398a5341d4259 100644
--- a/chrome/browser/chrome_browser_main_extra_parts_aura.cc
+++ b/chrome/browser/chrome_browser_main_extra_parts_aura.cc
@@ -3,10 +3,14 @@
 // found in the LICENSE file.
 
 #include "chrome/browser/chrome_browser_main_extra_parts_aura.h"
+
+#include "base/command_line.h"
 #include "chrome/browser/ui/views/aura/chrome_shell_delegate.h"
 #include "chrome/browser/ui/views/aura/screen_orientation_listener.h"
+#include "chrome/common/chrome_switches.h"
 #include "ui/aura/desktop.h"
 #include "ui/aura_shell/shell.h"
+#include "ui/gfx/compositor/compositor_setup.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/system/runtime_environment.h"
@@ -17,6 +21,9 @@ ChromeBrowserMainExtraPartsAura::ChromeBrowserMainExtraPartsAura()
 }
 
 void ChromeBrowserMainExtraPartsAura::PostBrowserProcessInit() {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kTestCompositor))
+    ui::SetupTestCompositor();
+
 #if defined(OS_CHROMEOS)
   if (chromeos::system::runtime_environment::IsRunningOnChromeOS())
     aura::Desktop::set_use_fullscreen_host_window(true);