Switch SurfaceId maps from base::hash_map to std::unordered_map.

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 fdfad179059d3eb1ea4e55b36d588a2f025b9994..cd8a0e38f7f99128965dae3cbcace05cfe906b58 100644
--- a/cc/surfaces/surface_factory.h
+++ b/cc/surfaces/surface_factory.h
@@ -6,6 +6,7 @@
 #define CC_SURFACES_SURFACE_FACTORY_H_
 
 #include <set>
+#include <unordered_map>
 
 #include "base/callback_forward.h"
 #include "base/containers/scoped_ptr_hash_map.h"
@@ -85,8 +86,8 @@ class CC_SURFACES_EXPORT SurfaceFactory
 
   bool needs_sync_points_;
 
-  typedef base::ScopedPtrHashMap<SurfaceId, scoped_ptr<Surface>>
-      OwningSurfaceMap;
+  using OwningSurfaceMap =
+      std::unordered_map<SurfaceId, scoped_ptr<Surface>, SurfaceIdHash>;
   OwningSurfaceMap surface_map_;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceFactory);