Pepper takes ownership of a mailbox before passing it to the texture layer.

gpu/ipc/client/command_buffer_proxy_impl.cc

Index: gpu/ipc/client/command_buffer_proxy_impl.cc
diff --git a/gpu/ipc/client/command_buffer_proxy_impl.cc b/gpu/ipc/client/command_buffer_proxy_impl.cc
index 7587212837fdca100c8ab632038e33b45ebce2b4..a79e490a69e4d5fc672c4faa6b82f5a3097ecfcf 100644
--- a/gpu/ipc/client/command_buffer_proxy_impl.cc
+++ b/gpu/ipc/client/command_buffer_proxy_impl.cc
@@ -617,13 +617,21 @@ void CommandBufferProxyImpl::SignalQuery(uint32_t query,
   signal_tasks_.insert(std::make_pair(signal_id, callback));
 }
 
-bool CommandBufferProxyImpl::ProduceFrontBuffer(const gpu::Mailbox& mailbox) {
-  CheckLock();
+void CommandBufferProxyImpl::TakeFrontBuffer(const gpu::Mailbox& mailbox) {

[piman, 2016/04/27 23:00:58]

nit: CheckLock();

[erikchen, 2016/04/27 23:59:24]

Done

[piman, 2016/04/28 02:15:05]

I don't see it in the latest PS (PS#18)

[erikchen, 2016/04/28 17:07:23]

I do see it.
https://codereview.chromium.org/1912833002/diff2/240001:330001/gpu/ipc/client...

It's been there since PS 15.

   if (last_state_.error != gpu::error::kNoError)
-    return false;
+    return;
 
-  Send(new GpuCommandBufferMsg_ProduceFrontBuffer(route_id_, mailbox));
-  return true;
+  Send(new GpuCommandBufferMsg_TakeFrontBuffer(route_id_, mailbox));
+}
+
+void CommandBufferProxyImpl::ReturnFrontBuffer(const gpu::Mailbox& mailbox,
+                                               const gpu::SyncToken& sync_token,
+                                               bool is_lost) {

[piman, 2016/04/27 23:00:58]

nit: CheckLock();

[erikchen, 2016/04/27 23:59:24]

Done.

[piman, 2016/04/28 02:15:05]

ditto

+  if (last_state_.error != gpu::error::kNoError)
+    return;
+
+  Send(new GpuCommandBufferMsg_ReturnFrontBuffer(route_id_, mailbox, sync_token,
+                                                 is_lost));
 }
 
 gpu::error::Error CommandBufferProxyImpl::GetLastError() {