cc: Give ownership of render passes to the renderer when drawing a frame.

cc/renderer.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_RENDERER_H_
 #define CC_RENDERER_H_
 
 #include "base/basictypes.h"
 #include "cc/cc_export.h"
 #include "cc/layer_tree_host.h"
@@ skipping 35 matching lines @@
 
     gfx::Size viewportSize() { return m_client->deviceViewportSize(); }
     int viewportWidth() { return viewportSize().width(); }
     int viewportHeight() { return viewportSize().height(); }
 
     virtual void viewportChanged() { }
 
     virtual void decideRenderPassAllocationsForFrame(const RenderPassList&) { }
     virtual bool haveCachedResourcesForRenderPassId(RenderPass::Id) const;
 
-    virtual void drawFrame(const RenderPassList&, const RenderPassIdHashMap&) = 0;
+    // This passes ownership of the render passes to the renderer. It should
+    // consume them, and empty the list and hash map.
+    virtual void drawFrame(RenderPassList&, RenderPassIdHashMap&) = 0;
 
     // waits for rendering to finish
     virtual void finish() = 0;
 
     virtual void doNoOp() { }
     // puts backbuffer onscreen
     virtual bool swapBuffers() = 0;
 
     virtual void getFramebufferPixels(void *pixels, const gfx::Rect&) = 0;
 
@@ skipping 10 matching lines @@
     }
 
     RendererClient* m_client;
 
     DISALLOW_COPY_AND_ASSIGN(Renderer);
 };
 
 }
 
 #endif  // CC_RENDERER_H_