Fix crash with pepper 3D on multiple windows in same renderer

content/renderer/ggl.cc

Index: content/renderer/ggl.cc
diff --git a/content/renderer/ggl.cc b/content/renderer/ggl.cc
index e73f50ddda464df9a10882ad5d2f930761799a9f..34c74dd377ac6ef117a87a8d16b9e2c3a907d77d 100644
--- a/content/renderer/ggl.cc
+++ b/content/renderer/ggl.cc
@@ -560,6 +560,14 @@ bool DestroyContext(Context* context) {
 #endif
 }
 
+base::WeakPtr<Context> GetWeakContextReference(Context* context) {
+#if defined(ENABLE_GPU)
+  return context ? context->AsWeakPtr() : base::WeakPtr<Context>();
+#else
+  return base::WeakPtr<Context>();
+#endif
+}
+
 media::VideoDecodeEngine* CreateVideoDecodeEngine(Context* context) {
   return context->CreateVideoDecodeEngine();
 }