ozone: Add post message loop initialization hook

ui/ozone/public/ozone_platform.cc

Index: ui/ozone/public/ozone_platform.cc
diff --git a/ui/ozone/public/ozone_platform.cc b/ui/ozone/public/ozone_platform.cc
index b69bc28927d76d800321b2f58b2c26c66759d21d..8d94029ca421d6e27ae49470d710e05870d3d91c 100644
--- a/ui/ozone/public/ozone_platform.cc
+++ b/ui/ozone/public/ozone_platform.cc
@@ -17,7 +17,7 @@ namespace {
 
 bool g_platform_initialized_ui = false;
 bool g_platform_initialized_gpu = false;
-
+bool g_platform_initialized_gpu_post_main_loop = false;
 }
 
 OzonePlatform::OzonePlatform() {
@@ -25,6 +25,7 @@ OzonePlatform::OzonePlatform() {
   instance_ = this;
   g_platform_initialized_ui = false;
   g_platform_initialized_gpu = false;
+  g_platform_initialized_gpu_post_main_loop = false;
 }
 
 OzonePlatform::~OzonePlatform() {
@@ -54,6 +55,18 @@ void OzonePlatform::InitializeForGPU() {
 }
 
 // static
+void OzonePlatform::InitializeForGpuPostMainLoop() {
+  DCHECK(g_platform_initialized_gpu) << "InitializeForGPU needs to be called "
+                                        "before InitializeForGpuPostMainLoop";
+  if (!base::MessageLoop::current() ||
+      g_platform_initialized_gpu_post_main_loop)
+    return;
+  g_platform_initialized_gpu_post_main_loop = true;
+
+  instance_->InitializeGpuPostMainLoop();
+}
+
+// static
 OzonePlatform* OzonePlatform::GetInstance() {
   DCHECK(instance_) << "OzonePlatform is not initialized";
   return instance_;