Add hints for potential overlay promotion on android.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index 6045e2c7684ce862275ca5b15b5d064c96eec363..eb679073b9f61c7ed5fec7a4f3a5e826026f61b7 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -2472,6 +2472,9 @@ void GLRenderer::DrawStreamVideoQuad(const DrawingFrame* frame,
       GetVideoStreamTextureProgram(tex_coord_precision);
   SetUseProgram(program->program());
 
+  bool is_promotable = IsResourcePromotable(quad->resource_id());

[liberato (no reviews please), 2016/11/19 18:25:52]

this is where i picture sending the message to the GLStreamTextureImage via
gl_->SomeCustomCommandCHROMIUM().

i tried to encapsulate this inside the overlay logic also, but it was a little
weird having to lock the resource, send in the context, etc.   getting all of
the 'is / is not promotable' logic into the overlay processor seemed like the
key idea from our mtg, so i didn't worry too much about moving notification
elsewhere.

please let me know if you'd prefer this to be moved.

[piman, 2016/11/23 00:37:25]

I guess it feels a bit odd to do here...
How about:
- ResourceProvider::SetPromotionHint(ResourceId resource, bool promote) which
internally can do the GL call (which should be straightforward after a few
DCHECKs, don't necessarily need the whole ScopedReadLockGL)
- pass the ResourceProvider to the
OverlayCandidateValidator::CheckOverlaySupport and have it issue the hints on
the resources you want to promote

[liberato (no reviews please), 2016/12/01 20:59:11]

i'll try to do that.

the trick is that OverlayCandidateValidator::CheckOverlaySupport doesn't know
what the correct hint is for the resource by the time it returns.  It has to
wait until all resources are processed to see if any are promoted, since we'll
promote at most one.  promotable resources become unpromotable if some other
resource is actually promoted.

i really don't like having CheckOverlaySupport have this stateful set of
resources that i added.  i'll try to get rid of that too, since it really goes
with the candidate list.

+  LOG(ERROR) << "AVDA: " << __FUNCTION__ << ": promotable: " << is_promotable;
+
   ToGLMatrix(&gl_matrix[0], quad->matrix);
 
   ResourceProvider::ScopedReadLockGL lock(resource_provider_,