gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/mapped_memory.cc

Index: gpu/command_buffer/client/mapped_memory.cc
diff --git a/gpu/command_buffer/client/mapped_memory.cc b/gpu/command_buffer/client/mapped_memory.cc
index 15584aaaf07daebf1bf20ba5225e086bfc1da4db..e9b0a1d3a4f5ce7472861721b32cc748e01f04ba 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -117,6 +117,18 @@ void MappedMemoryManager::FreePendingToken(void* pointer, int32 token) {
   NOTREACHED();
 }
 
+void MappedMemoryManager::FreePendingAsyncToken(void *pointer,
+                                                uint32 async_token) {
+  for (size_t ii = 0; ii < chunks_.size(); ++ii) {
+    MemoryChunk* chunk = chunks_[ii];
+    if (chunk->IsInChunk(pointer)) {
+      chunk->FreePendingAsyncToken(pointer, async_token);
+      return;
+    }
+  }
+  NOTREACHED();
+}
+
 void MappedMemoryManager::FreeUnused() {
   CommandBuffer* cmd_buf = helper_->command_buffer();
   MemoryChunkVector::iterator iter = chunks_.begin();