Fix race in HostSharedBitmapManager::AllocatedBitmapCount

content/common/host_shared_bitmap_manager.h

Index: content/common/host_shared_bitmap_manager.h
diff --git a/content/common/host_shared_bitmap_manager.h b/content/common/host_shared_bitmap_manager.h
index 08245b368b58191e5288576840db6c117ce2b84f..5559a85f3eab78a43975973d925aa310754b849d 100644
--- a/content/common/host_shared_bitmap_manager.h
+++ b/content/common/host_shared_bitmap_manager.h
@@ -65,12 +65,12 @@ class CONTENT_EXPORT HostSharedBitmapManager : public cc::SharedBitmapManager {
   void ChildDeletedSharedBitmap(const cc::SharedBitmapId& id);
   void ProcessRemoved(base::ProcessHandle process_handle);
 
-  size_t AllocatedBitmapCount() const { return handle_map_.size(); }
+  size_t AllocatedBitmapCount() const;
 
  private:
   void FreeSharedMemoryFromMap(cc::SharedBitmap* bitmap);
 
-  base::Lock lock_;
+  mutable base::Lock lock_;
 
   typedef base::hash_map<cc::SharedBitmapId, scoped_refptr<BitmapData> >
       BitmapMap;