cc: Use the correct internal format for glCopyTexImage2D calls.

blimp/client/feature/compositor/blimp_output_surface.cc

Index: blimp/client/feature/compositor/blimp_output_surface.cc
diff --git a/blimp/client/feature/compositor/blimp_output_surface.cc b/blimp/client/feature/compositor/blimp_output_surface.cc
index 14cf68226520f629a592f9489a39767c332be2b8..092b712bdd6adc32b6ae759e672cb9d389c7e887 100644
--- a/blimp/client/feature/compositor/blimp_output_surface.cc
+++ b/blimp/client/feature/compositor/blimp_output_surface.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
+#include "blimp/client/feature/compositor/blimp_context_provider.h"
 #include "cc/output/output_surface_client.h"
 #include "gpu/command_buffer/client/context_support.h"
 
@@ -13,7 +14,7 @@ namespace blimp {
 namespace client {
 
 BlimpOutputSurface::BlimpOutputSurface(
-    scoped_refptr<cc::ContextProvider> context_provider)
+    scoped_refptr<BlimpContextProvider> context_provider)
     : cc::OutputSurface(std::move(context_provider), nullptr, nullptr) {}
 
 BlimpOutputSurface::~BlimpOutputSurface() {}
@@ -25,5 +26,10 @@ void BlimpOutputSurface::SwapBuffers(cc::CompositorFrame* frame) {
   cc::OutputSurface::PostSwapBuffersComplete();
 }
 
+uint32_t BlimpOutputSurface::GetFramebufferCopyTextureFormat() {
+  auto* gl = static_cast<BlimpContextProvider*>(context_provider());
+  return gl->GetCopyTextureInternalFormat();
+}
+
 }  // namespace client
 }  // namespace blimp