Avoid GpuPreferences exposed in content public gpu interface

content/gpu/gpu_child_thread.h

Index: content/gpu/gpu_child_thread.h
diff --git a/content/gpu/gpu_child_thread.h b/content/gpu/gpu_child_thread.h
index e5f518972faf543c123e61f551858ef3594f9e97..ab05e5b2a80c06253106f8cd7f545fb08ae52ec1 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -56,6 +56,10 @@ class GpuChildThread : public ChildThreadImpl,
  public:
   typedef std::queue<IPC::Message*> DeferredMessages;
 
+  // Returns the one gpu thread for this process. Note that this can only
+  // be accessed when running on the gpu thread itself.
+  static GpuChildThread* current();
+
   GpuChildThread(GpuWatchdogThread* gpu_watchdog_thread,
                  bool dead_on_arrival,
                  const gpu::GPUInfo& gpu_info,
@@ -75,6 +79,8 @@ class GpuChildThread : public ChildThreadImpl,
   void Init(const base::Time& process_start_time);
   void StopWatchdog();
 
+  gpu::GpuPreferences gpu_preferences() { return gpu_preferences_; }
+
  private:
   // ChildThread overrides.
   bool Send(IPC::Message* msg) override;