gpu: Maintain the deferred log messages separately from the IPC messages.

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 3882fa526d254ce6886bdd9ae77b81ed21f32c7a..3e2b99e8b48e2f06e7be1d59e4ed0e3701de8bac 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -56,7 +56,12 @@ class GpuChildThread : public ChildThreadImpl,
                        public gpu::GpuChannelManagerDelegate,
                        public base::FieldTrialList::Observer {
  public:
-  typedef std::queue<IPC::Message*> DeferredMessages;
+  struct LogMessage {
+    int severity;
+    std::string header;
+    std::string message;
+  };
+  typedef std::queue<LogMessage> DeferredMessages;
 
   GpuChildThread(std::unique_ptr<gpu::GpuWatchdogThread> gpu_watchdog_thread,
                  bool dead_on_arrival,