mus::GpuService: Support establish GpuChannel asynchronously.

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index 8c90372bed2931a50d01a8404fec70de81c6e0ff..c4c4c212117e352c0bffc93ec6a3e62ff27b3108 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -191,6 +191,10 @@
 #include "gpu/vulkan/vulkan_implementation.h"
 #endif
 
+#if defined(MOJO_SHELL_CLIENT)
+#include "components/mus/common/gpu_service.h"
+#endif
+
 // One of the linux specific headers defines this as a macro.
 #ifdef DestroyAll
 #undef DestroyAll
@@ -1171,8 +1175,11 @@ int BrowserMainLoop::BrowserThreadsStarted() {
 #if defined(MOJO_SHELL_CLIENT) && defined(USE_AURA)
     // TODO(rockot): Remove the blocking wait for init.
     // http://crbug.com/594852.
-    if (MojoShellConnection::GetForProcess())
+    auto connection = MojoShellConnection::GetForProcess();
+    if (connection) {
       WaitForMojoShellInitialize();
+      mus::GpuService::GetInstance()->Initialize(connection->GetConnector());
+    }
 #endif
   }