[Android WebView] Implement Ubercomp for Render Thread support

android_webview/browser/aw_browser_main_parts.cc

Index: android_webview/browser/aw_browser_main_parts.cc
diff --git a/android_webview/browser/aw_browser_main_parts.cc b/android_webview/browser/aw_browser_main_parts.cc
index 653f8c5f90816c7d1c6d1554ebdfe84fb7244c6d..d6565a07956f04cfc2cc8fa70a7ccd1b523957af 100644
--- a/android_webview/browser/aw_browser_main_parts.cc
+++ b/android_webview/browser/aw_browser_main_parts.cc
@@ -6,6 +6,7 @@
 
 #include "android_webview/browser/aw_browser_context.h"
 #include "android_webview/browser/aw_result_codes.h"
+#include "android_webview/common/aw_switches.h"
 #include "base/android/build_info.h"
 #include "base/android/memory_pressure_listener_android.h"
 #include "base/command_line.h"
@@ -62,7 +63,8 @@ int AwBrowserMainParts::PreCreateThreads() {
 }
 
 void AwBrowserMainParts::PreMainMessageLoopRun() {
-  if (!gpu::gles2::MailboxSynchronizer::Initialize()) {
+  if (!switches::UbercompEnabled() &&
+      !gpu::gles2::MailboxSynchronizer::Initialize()) {
     CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kDisableAccelerated2dCanvas);
   }