ui: Cleanup class/struct forward declarations

cc/surfaces/surface_factory.h

Index: cc/surfaces/surface_factory.h
diff --git a/cc/surfaces/surface_factory.h b/cc/surfaces/surface_factory.h
index f392db20f23df6655efe21074abedfe1c446eddb..3a6431596bc9cc470e8ef4fdbae1520988543e14 100644
--- a/cc/surfaces/surface_factory.h
+++ b/cc/surfaces/surface_factory.h
@@ -35,8 +35,7 @@ class SurfaceManager;
 // submitted to frames created by a particular factory will be returned to that
 // factory's client when they are no longer being used. This is the only class
 // most users of surfaces will need to directly interact with.
-class CC_SURFACES_EXPORT SurfaceFactory
-    : public base::SupportsWeakPtr<SurfaceFactory> {
+class CC_SURFACES_EXPORT SurfaceFactory {
  public:
   using DrawCallback = base::Callback<void()>;
 
@@ -49,8 +48,14 @@ class CC_SURFACES_EXPORT SurfaceFactory
 
   void Create(const LocalFrameId& local_frame_id);
   void Destroy(const LocalFrameId& local_frame_id);
+
+  // Destroys all surfaces.
   void DestroyAll();
 
+  // Destroys and disown all surfaces, and reset all resource references. This
+  // is useful when resources are invalid (e.g. lost context).
+  void Reset();
+
   // Set that the current frame on new_id is to be treated as the successor to
   // the current frame on old_id for the purposes of calculating damage.
   void SetPreviousFrameSurface(const LocalFrameId& new_id,
@@ -98,6 +103,8 @@ class CC_SURFACES_EXPORT SurfaceFactory
       unordered_map<LocalFrameId, std::unique_ptr<Surface>, LocalFrameIdHash>;
   OwningSurfaceMap surface_map_;
 
+  base::WeakPtrFactory<SurfaceFactory> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(SurfaceFactory);
 };