gpu: Use mus gpu interface in non-mus chrome.

content/gpu/gpu_main.cc

Index: content/gpu/gpu_main.cc
diff --git a/content/gpu/gpu_main.cc b/content/gpu/gpu_main.cc
index 668be833a27d97923a11ca8ee2378766e258d466..54791f60a1c8d8591c74e856c0562fd20a2d0d16 100644
--- a/content/gpu/gpu_main.cc
+++ b/content/gpu/gpu_main.cc
@@ -262,8 +262,8 @@ int GpuMain(const MainFunctionParams& parameters) {
   // is implemented using an IPC channel error. If the IPC channel is not fully
   // set up between the browser and GPU process, and the GPU process crashes or
   // exits early, the browser process will never detect it.  For this reason we
-  // defer tearing down the GPU process until receiving the GpuMsg_Initialize
-  // message from the browser.
+  // defer tearing down the GPU process until receiving the initialization
+  // message from the browser (through mojom::GpuMain::CreateGpuService()).
   const bool init_success = gpu_init.InitializeAndStartSandbox(command_line);
   const bool dead_on_arrival = !init_success;