Allow DrawingBuffer to present to a bitmap.

public/platform/WebExternalTextureLayerClient.h

Index: public/platform/WebExternalTextureLayerClient.h
diff --git a/public/platform/WebExternalTextureLayerClient.h b/public/platform/WebExternalTextureLayerClient.h
index 4829600c21f94fd14262fd417331b98c55995be2..86cf5af3387ba46fd5069f44c372db8f320994e0 100644
--- a/public/platform/WebExternalTextureLayerClient.h
+++ b/public/platform/WebExternalTextureLayerClient.h
@@ -32,6 +32,7 @@
 namespace WebKit {
 
 class WebGraphicsContext3D;
+class WebExternalBitmap;
 struct WebExternalTextureMailbox;
 
 class WebTextureUpdater {
@@ -49,7 +50,11 @@ public:
 
     // Returns true and provides a mailbox if a new frame is available.
     // Returns false if no new data is available and the old mailbox is to be reused.
-    virtual bool prepareMailbox(WebExternalTextureMailbox*) = 0;
+    virtual bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) = 0;

[jochen (gone - plz use gerrit), 2013/07/02 22:37:01]

nit. WebExternalBitmap* = 0, then you don't need the overloaded method

+
+    // OBSOLETE.
+    // FIXME: remove when the users are removed. https://code.google.com/p/chromium/issues/detail?id=151713
+    virtual bool prepareMailbox(WebExternalTextureMailbox* mailbox) { return prepareMailbox(mailbox, 0); }
 
     // Notifies the client when a mailbox is no longer in use by the compositor and provides
     // a sync point to wait on before the mailbox could be consumes again by the client.