Add calls to EnsureGPUMemoryAvailable into GLES2DecoderImpl

gpu/command_buffer/service/renderbuffer_manager.h

Index: gpu/command_buffer/service/renderbuffer_manager.h
diff --git a/gpu/command_buffer/service/renderbuffer_manager.h b/gpu/command_buffer/service/renderbuffer_manager.h
index b64fd7d6195d0dfa92481a00cae2d9bf55f26593..7107493712685b62d14141a889e9ff4db680d321 100644
--- a/gpu/command_buffer/service/renderbuffer_manager.h
+++ b/gpu/command_buffer/service/renderbuffer_manager.h
@@ -170,6 +170,10 @@ class GPU_EXPORT RenderbufferManager {
     return memory_tracker_->GetMemRepresented();
   }
 
+  static bool ComputeEstimatedRenderbufferSize(
+      int width, int height, int samples, int internal_format, uint32* size);
+  static GLenum InternalRenderbufferFormatToImplFormat(GLenum impl_format);
+
  private:
   void StartTracking(RenderbufferInfo* renderbuffer);
   void StopTracking(RenderbufferInfo* renderbuffer);