Add compositor support for half-float RGBA buffers and textures

cc/output/output_surface.cc

Index: cc/output/output_surface.cc
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 9c86c08a80bdd5de6740ff065c72b70aac8ecb47..30f8c04abdabcfd4d81b1b83559fb61c59830b75 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -36,6 +36,10 @@ OutputSurface::OutputSurface(
   DCHECK(vulkan_context_provider_);
 }
 
+bool OutputSurface::IsHighBitDepth() const {
+  return true;

[enne (OOO), 2017/02/01 23:55:22]

I'm a little surprised you return true by default here.  <_<

[ccameron, 2017/02/02 21:08:41]

I'm not 100% sure this is the right interface, so I've removed it and replaced
it with a TODO.

+}
+
 OutputSurface::~OutputSurface() = default;
 
 }  // namespace cc