mash: Migrate tray IME view to wm common types, move to //ash/common

ash/mus/bridge/wm_shell_mus.h

Index: ash/mus/bridge/wm_shell_mus.h
diff --git a/ash/mus/bridge/wm_shell_mus.h b/ash/mus/bridge/wm_shell_mus.h
index 86e87c280c87eeeaf34b12ee41f6224102c20ca4..58bef5c46ce4f9ffab418881623afb03a6ed7a8d 100644
--- a/ash/mus/bridge/wm_shell_mus.h
+++ b/ash/mus/bridge/wm_shell_mus.h
@@ -67,6 +67,7 @@ class WmShellMus : public WmShell, public ::mus::WindowTreeClientObserver {
   void OnOverviewModeEnded() override;
   bool IsOverviewModeSelecting() override;
   bool IsOverviewModeRestoringMinimizedWindows() override;
+  void ToggleIgnoreExternalKeyboard() override;
   AccessibilityDelegate* GetAccessibilityDelegate() override;
   SessionStateDelegate* GetSessionStateDelegate() override;
   void AddActivationObserver(WmActivationObserver* observer) override;