gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/mapped_memory.h

Index: gpu/command_buffer/client/mapped_memory.h
diff --git a/gpu/command_buffer/client/mapped_memory.h b/gpu/command_buffer/client/mapped_memory.h
index b8f3129eb4a3cddf452e9fabe30ec62a1af12eda..5f1b682d010a3d8eddd5c9796bccaa3ef94aa959 100644
--- a/gpu/command_buffer/client/mapped_memory.h
+++ b/gpu/command_buffer/client/mapped_memory.h
@@ -79,6 +79,10 @@ class GPU_EXPORT MemoryChunk {
     allocator_.FreePendingToken(pointer, token);
   }
 
+  void FreePendingSerial(void* pointer, uint32 serial) {
+    allocator_.FreePendingSerial(pointer, serial);
+  }
+
   // Frees any blocks whose tokens have passed.
   void FreeUnused() {
     allocator_.FreeUnused();
@@ -153,6 +157,8 @@ class GPU_EXPORT MappedMemoryManager {
   //   token: the token value to wait for before re-using the memory.
   void FreePendingToken(void* pointer, int32 token);
 
+  void FreePendingSerial(void *pointer, uint32 serial);
+
   // Free Any Shared memory that is not in use.
   void FreeUnused();