Mojo multiple command buffer support and sample

mojo/services/public/interfaces/native_viewport/native_viewport.mojom

Index: mojo/services/public/interfaces/native_viewport/native_viewport.mojom
diff --git a/mojo/services/public/interfaces/native_viewport/native_viewport.mojom b/mojo/services/public/interfaces/native_viewport/native_viewport.mojom
index b168104a704be40bcf438f5d1c68b0ee557c74c4..4a083bfbe80ec485cf5e3a787f2772eccb92ca4f 100644
--- a/mojo/services/public/interfaces/native_viewport/native_viewport.mojom
+++ b/mojo/services/public/interfaces/native_viewport/native_viewport.mojom
@@ -16,6 +16,7 @@ interface NativeViewport {
   Close();
   SetBounds(Rect bounds);
   CreateGLES2Context(CommandBuffer& gles2_client);
+  CreateOffscreenGLES2Context(CommandBuffer& gles2_client);

[darin (slow to review), 2014/08/13 04:44:25]

Is it necessary for this to be supplied by the NativeViewport? I could imagine a
use case for providing an app with access to GL but no access to the screen.
This might be used for compute tasks, etc. Access control is likely to be at the
per-interface level rather than at the per-method level.

Maybe this is something that could be changed later, but I'm curious if we
shouldn't separate these more from the start.

 };
 
 interface NativeViewportClient {