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..cefeefd2b24eb0cf40dab05ea6854bd0e47f4e3f 100644
--- a/gpu/ipc/client/command_buffer_proxy_impl.cc
+++ b/gpu/ipc/client/command_buffer_proxy_impl.cc
@@ -617,15 +617,39 @@ void CommandBufferProxyImpl::SignalQuery(uint32_t query,
   signal_tasks_.insert(std::make_pair(signal_id, callback));
 }
 
-bool CommandBufferProxyImpl::ProduceFrontBuffer(const gpu::Mailbox& mailbox) {
-  CheckLock();
+bool CommandBufferProxyImpl::TakeFrontBuffer(const gpu::Mailbox& mailbox,
+                                             gpu::SyncToken* sync_token) {
+  scoped_ptr<base::AutoLock> lock;
+  if (lock_)
+    lock.reset(new base::AutoLock(*lock_));
   if (last_state_.error != gpu::error::kNoError)
     return false;
 
-  Send(new GpuCommandBufferMsg_ProduceFrontBuffer(route_id_, mailbox));
+  Send(new GpuCommandBufferMsg_TakeFrontBuffer(route_id_, mailbox));
+
+  uint64_t fence = GenerateFenceSyncRelease();
+  *sync_token = gpu::SyncToken(GetNamespaceID(), GetExtraCommandBufferData(),
+                               GetCommandBufferID(), fence);
+
+  // Force a synchronous IPC to validate sync token.
+  EnsureWorkVisible();
+  sync_token->SetVerifyFlush();
   return true;
 }
 
+void CommandBufferProxyImpl::ReturnFrontBuffer(const gpu::Mailbox& mailbox,
+                                               const gpu::SyncToken& sync_token,
+                                               bool is_lost) {
+  scoped_ptr<base::AutoLock> lock;
+  if (lock_)
+    lock.reset(new base::AutoLock(*lock_));
+  if (last_state_.error != gpu::error::kNoError)
+    return;
+
+  Send(new GpuCommandBufferMsg_ReturnFrontBuffer(route_id_, mailbox, sync_token,
+                                                 is_lost));
+}
+
 gpu::error::Error CommandBufferProxyImpl::GetLastError() {
   return last_state_.error;
 }