cc: Introduce mechanism to observe CompositorFrames submitted to new surfaceIDs

cc/surfaces/surface_observer.h

+// Copyright 2016 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_SURFACES_SURFACE_OBSERVER_H_
+#define CC_SURFACES_SURFACE_OBSERVER_H_
+
+namespace gfx {
+class Size;
+}
+
+namespace cc {
+
+class SurfaceId;
+
+class SurfaceObserver {
+ public:
+  // Runs when a CompositorFrame is received for the given |surface_id| for the
+  // first time.
+  virtual void OnSurfaceCreated(const SurfaceId& surface_id,
+                                const gfx::Size& frame_size,
+                                float device_scale_factor) = 0;
+
+  // Runs when a Surface is damaged. *changed should be set to true if this
+  // causes a Display to be damaged.
+  virtual void OnSurfaceDamaged(const SurfaceId& surface_id, bool* changed) = 0;
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_SURFACE_OBSERVER_H_