Create ash media delegate earlier during ash shell initialization

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index a1b8d99259d16ce0077b11309bc44b47b0ee7977..bb012d7abb237310a4c141fbfe0bbdaf163b45e2 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -42,6 +42,12 @@ WmShell* WmShell::Get() {
   return instance_;
 }
 
+void WmShell::Initialize() {
+  // Some delegates access WmShell during their construction. Create them here
+  // instead of the WmShell constructor.
+  media_delegate_.reset(delegate_->CreateMediaDelegate());
+}
+
 void WmShell::OnMaximizeModeStarted() {
   FOR_EACH_OBSERVER(ShellObserver, shell_observers_, OnMaximizeModeStarted());
 }
@@ -105,10 +111,6 @@ void WmShell::SetKeyboardUI(std::unique_ptr<KeyboardUI> keyboard_ui) {
   keyboard_ui_ = std::move(keyboard_ui);
 }
 
-void WmShell::SetMediaDelegate(std::unique_ptr<MediaDelegate> delegate) {
-  media_delegate_ = std::move(delegate);
-}
-
 void WmShell::SetSystemTrayDelegate(
     std::unique_ptr<SystemTrayDelegate> delegate) {
   DCHECK(delegate);