cc: Implement shared worker contexts. (v1)

content/browser/compositor/gpu_process_transport_factory.cc

Index: content/browser/compositor/gpu_process_transport_factory.cc
diff --git a/content/browser/compositor/gpu_process_transport_factory.cc b/content/browser/compositor/gpu_process_transport_factory.cc
index 4c0b3630df7eaa3c2565da02b28c9161b2467e5a..bf1af95fb043f29ae89322d9949d107b9c74f470 100644
--- a/content/browser/compositor/gpu_process_transport_factory.cc
+++ b/content/browser/compositor/gpu_process_transport_factory.cc
@@ -265,6 +265,13 @@ void GpuProcessTransportFactory::EstablishedGpuChannel(
         if (shared_worker_context_provider_ &&
             !shared_worker_context_provider_->BindToCurrentThread())
           shared_worker_context_provider_ = nullptr;
+
+        if (shared_worker_context_provider_) {
+          shared_worker_context_provider_->SetupLock();
+          // Detach from thread to allow context to be destroyed on a
+          // different thread without being used.
+          shared_worker_context_provider_->DetachFromThread();
+        }
       }
     }