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..8393c6f65a1fde3f31d850bcb38375d31c6fea82 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -117,6 +117,17 @@ void MappedMemoryManager::FreePendingToken(void* pointer, int32 token) {
   NOTREACHED();
 }
 
+void MappedMemoryManager::FreePendingSerial(void *pointer, uint32 serial) {
+  for (size_t ii = 0; ii < chunks_.size(); ++ii) {
+    MemoryChunk* chunk = chunks_[ii];
+    if (chunk->IsInChunk(pointer)) {
+      chunk->FreePendingSerial(pointer, serial);
+      return;
+    }
+  }
+  NOTREACHED();
+}
+
 void MappedMemoryManager::FreeUnused() {
   CommandBuffer* cmd_buf = helper_->command_buffer();
   MemoryChunkVector::iterator iter = chunks_.begin();