gpu: Defer reads from default framebuffer when needed.

gpu/command_buffer/client/gles2_implementation_impl_autogen.h

Index: gpu/command_buffer/client/gles2_implementation_impl_autogen.h
diff --git a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
index 4ce044e1e4e281b539aaaedf3008b8b96373b584..e15ebd0c4ecc8caf2a7a3b6e173a7e74d17f75c0 100644
--- a/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
+++ b/gpu/command_buffer/client/gles2_implementation_impl_autogen.h
@@ -117,6 +117,12 @@ GLenum GLES2Implementation::CheckFramebufferStatus(GLenum target) {
   return *result;
 }
 
+void GLES2Implementation::Clear(GLbitfield mask) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glClear(" << mask << ")");
+  helper_->Clear(mask);
+}
+
 void GLES2Implementation::ClearColor(
     GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha) {
   GPU_CLIENT_SINGLE_THREAD_CHECK();