Allow WebExternalTextureLayerClient to work with mailboxes.

cc/texture_layer_client.h

Index: cc/texture_layer_client.h
diff --git a/cc/texture_layer_client.h b/cc/texture_layer_client.h
index ec3447fee664fac68fe0a0760e6f80b56d2c88d5..2d0f915b3a93d02b2f2b6bf001cffed6a73bdc55 100644
--- a/cc/texture_layer_client.h
+++ b/cc/texture_layer_client.h
@@ -11,6 +11,7 @@ class WebGraphicsContext3D;
 
 namespace cc {
 class ResourceUpdateQueue;
+class TextureMailbox;
 
 class TextureLayerClient {
 public:
@@ -22,6 +23,8 @@ public:
     // Returns the context that is providing the texture. Used for rate limiting and detecting lost context.
     virtual WebKit::WebGraphicsContext3D* context() = 0;
 
+    virtual bool prepareTextureMailbox(TextureMailbox*) = 0;

[piman, 2013/03/14 19:54:58]

Definitely worth a comment. In particular the meaning of the return value (false
== reuse existing).

+
 protected:
     virtual ~TextureLayerClient() { }
 };