cc: Remove SurfaceDependencies type

cc/surfaces/surface_dependency_tracker.cc

 // 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.
 
 #include "cc/surfaces/surface_dependency_tracker.h"
 
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_info.h"
 #include "cc/surfaces/surface_manager.h"
 
@@ skipping 141 matching lines @@
 }
 
 void SurfaceDependencyTracker::OnSurfaceActivated(Surface* surface) {
   surface->RemoveObserver(this);
   observed_surfaces_by_id_.erase(surface->surface_id());
   NotifySurfaceIdAvailable(surface->surface_id());
 }
 
 void SurfaceDependencyTracker::OnSurfaceDependenciesChanged(
     Surface* surface,
-    const SurfaceDependencies& added_dependencies,
-    const SurfaceDependencies& removed_dependencies) {
+    const base::flat_set<SurfaceId>& added_dependencies,
+    const base::flat_set<SurfaceId>& removed_dependencies) {
   // Update the |blocked_surfaces_from_dependency_| map with the changes in
   // dependencies.
   for (const SurfaceId& surface_id : added_dependencies)
     blocked_surfaces_from_dependency_[surface_id].insert(surface->surface_id());
 
   for (const SurfaceId& surface_id : removed_dependencies) {
     auto it = blocked_surfaces_from_dependency_.find(surface_id);
     it->second.erase(surface->surface_id());
     if (it->second.empty())
       blocked_surfaces_from_dependency_.erase(it);
@@ skipping 40 matching lines @@
       // A blocked surface may have been garbage collected during dependency
       // resolution.
       DCHECK(!observed_surfaces_by_id_.count(blocked_surface_by_id));
       continue;
     }
     blocked_surface->NotifySurfaceIdAvailable(surface_id);
   }
 }
 
 }  // namespace cc