cc: Use the correct internal format for glCopyTexImage2D calls.

blimp/client/feature/compositor/blimp_context_provider.h

Index: blimp/client/feature/compositor/blimp_context_provider.h
diff --git a/blimp/client/feature/compositor/blimp_context_provider.h b/blimp/client/feature/compositor/blimp_context_provider.h
index dbcafcd62c4763397af3a9d0ca9fafcd1a493834..ffdb5d7de5d506c1b9f128105247897b449ab83e 100644
--- a/blimp/client/feature/compositor/blimp_context_provider.h
+++ b/blimp/client/feature/compositor/blimp_context_provider.h
@@ -43,6 +43,8 @@ class BlimpContextProvider : public cc::ContextProvider {
   void SetLostContextCallback(
       const LostContextCallback& lost_context_callback) override;
 
+  uint32_t GetCopyTextureInternalFormat();

[Wez, 2016/06/22 21:02:21]

nit: Please add a comment e.g. "Returns the GL texture format, for use by the
owning OutputSurface implementation." so it's clear why we need this here, in
addition to the ContextProvider interface.

nit: Should ContextProvider interface have this method too, so this becomes an
override? Are there ContextProviders for which the texture format is not
relevant, or is well-known to the caller..?

[danakj, 2016/06/22 21:06:50]

Done, here and on the other context providers too.
Since every place that wants this data knows the concrete type of the
ContextProvider, I'd rather not make it part of the general API.

[Wez, 2016/06/22 21:08:14]

Acknowledged.

+
  protected:
   BlimpContextProvider(
       gfx::AcceleratedWidget widget,