cc: Route offscreen context creation for compositor to the browser.

cc/resource_provider.h

Index: cc/resource_provider.h
diff --git a/cc/resource_provider.h b/cc/resource_provider.h
index 5b31139bdee2748d7afe8febd68db9ac9b609831..e63093c654e850966c6e22e94f2e972e5b4a3867 100644
--- a/cc/resource_provider.h
+++ b/cc/resource_provider.h
@@ -35,6 +35,7 @@ class Vector2d;
 
 namespace cc {
 
+class ContextProvider;
 class TextureUploader;
 
 // This class is not thread-safe and can only be called from the thread it was
@@ -263,6 +264,9 @@ public:
     // Indicates if we can currently lock this resource for write.
     bool canLockForWrite(ResourceId);
 
+    cc::ContextProvider* offscreenContextProvider() { return m_offscreenContextProvider.get(); }
+    void setOffscreenContextProvider(scoped_refptr<cc::ContextProvider> offscreenContextProvider);
+
 private:
     struct Resource {
         Resource();
@@ -334,6 +338,8 @@ private:
     int m_maxTextureSize;
     GLenum m_bestTextureFormat;
 
+    scoped_refptr<cc::ContextProvider> m_offscreenContextProvider;
+
     base::ThreadChecker m_threadChecker;
 
     scoped_refptr<Fence> m_currentReadLockFence;