gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/buffer_tracker.cc

Index: gpu/command_buffer/client/buffer_tracker.cc
diff --git a/gpu/command_buffer/client/buffer_tracker.cc b/gpu/command_buffer/client/buffer_tracker.cc
index 18cedb975d059664d421d5e65f11a982a39a474b..5b0f8bafa7e53b0a669cfabbe2b4e337950af978 100644
--- a/gpu/command_buffer/client/buffer_tracker.cc
+++ b/gpu/command_buffer/client/buffer_tracker.cc
@@ -60,8 +60,29 @@ void BufferTracker::FreePendingToken(Buffer* buffer, int32 token) {
   buffer->shm_id_ = 0;
   buffer->shm_offset_ = 0;
   buffer->address_ = NULL;
+  buffer->last_usage_token_ = 0;
 }
 
+void BufferTracker::FreePendingSerial(Buffer* buffer, uint32 serial) {
+  if (buffer->address_)
+    mapped_memory_->FreePendingSerial(buffer->address_, serial);
+  buffer->size_ = 0;
+  buffer->shm_id_ = 0;
+  buffer->shm_offset_ = 0;
+  buffer->address_ = NULL;
+  buffer->last_usage_token_ = 0;
+}
+
+void BufferTracker::Free(Buffer* buffer) {
+  if (buffer->address_)
+    mapped_memory_->Free(buffer->address_);
+
+  buffer->size_ = 0;
+  buffer->shm_id_ = 0;
+  buffer->shm_offset_ = 0;
+  buffer->address_ = NULL;
+  buffer->last_usage_token_ = 0;
+}
 
 }  // namespace gles2
 }  // namespace gpu