Allow multiple logging::LogMessage{Handler,Listener}s

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 8d10a630c7f5196cff5a4c316f04022ba7be0ec1..78ddf09f785c4f7464d935c2c64f36367fc4320d 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -45,6 +45,11 @@ class TargetServices;
 
 namespace content {
 class GpuProcessControlImpl;
+class GpuProcessLogMessageListener : logging::LogMessageListener {
+ public:
+  void OnMessage(int severity, const char* file, int line,
+      size_t message_start, const std::string& str) override;
+};
 class GpuWatchdogThread;
 struct EstablishChannelParams;
 
@@ -170,6 +175,8 @@ class GpuChildThread : public ChildThreadImpl,
   // Bindings to the mojom::ProcessControl impl.
   mojo::BindingSet<mojom::ProcessControl> process_control_bindings_;
 
+  std::unique_ptr<GpuProcessLogMessageListener> log_listener_;
+
   DISALLOW_COPY_AND_ASSIGN(GpuChildThread);
 };