[Reland 2] 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 5a27425db0b968332acfcb913e236ba6f3d4d9cf..f5b7c481de88ba2b7472ea78b77794a15948edb1 100644
--- a/gpu/ipc/client/command_buffer_proxy_impl.cc
+++ b/gpu/ipc/client/command_buffer_proxy_impl.cc
@@ -612,13 +612,23 @@ void CommandBufferProxyImpl::SignalQuery(uint32_t query,
   signal_tasks_.insert(std::make_pair(signal_id, callback));
 }
 
-bool CommandBufferProxyImpl::ProduceFrontBuffer(const gpu::Mailbox& mailbox) {
+void CommandBufferProxyImpl::TakeFrontBuffer(const gpu::Mailbox& mailbox) {
   CheckLock();
   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) {
+  CheckLock();
+  if (last_state_.error != gpu::error::kNoError)
+    return;
+
+  Send(new GpuCommandBufferMsg_WaitSyncToken(route_id_, sync_token));
+  Send(new GpuCommandBufferMsg_ReturnFrontBuffer(route_id_, mailbox, is_lost));
 }
 
 gpu::error::Error CommandBufferProxyImpl::GetLastError() {