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

content/gpu/gpu_child_thread.cc

Index: content/gpu/gpu_child_thread.cc
diff --git a/content/gpu/gpu_child_thread.cc b/content/gpu/gpu_child_thread.cc
index cc97e948cf2febe7cadb8da5c8e0296378be4668..ff308ff1a0554d47f2e6c952d71b23eca130493b 100644
--- a/content/gpu/gpu_child_thread.cc
+++ b/content/gpu/gpu_child_thread.cc
@@ -218,7 +218,8 @@ GpuChildThread::~GpuChildThread() {
 
 void GpuChildThread::Shutdown() {
   ChildThreadImpl::Shutdown();
-  logging::SetLogMessageHandler(NULL);
+  if (!in_browser_process_)
+    logging::PopLogMessageHandler();
 }
 
 void GpuChildThread::Init(const base::Time& process_start_time) {
@@ -374,7 +375,7 @@ void GpuChildThread::OnInitialize(const gpu::GpuPreferences& gpu_preferences) {
   // We don't need to pipe log messages if we are running the GPU thread in
   // the browser process.
   if (!in_browser_process_)
-    logging::SetLogMessageHandler(GpuProcessLogMessageHandler);
+    logging::PushLogMessageHandler(GpuProcessLogMessageHandler);
 
   gpu::SyncPointManager* sync_point_manager = nullptr;
   // Note SyncPointManager from ContentGpuClient cannot be owned by this.