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

ash/mus/bridge/wm_shell_mus.cc

Index: ash/mus/bridge/wm_shell_mus.cc
diff --git a/ash/mus/bridge/wm_shell_mus.cc b/ash/mus/bridge/wm_shell_mus.cc
index d21336b84eac59255eda2890f2c96d4d1372c555..cc4b806dfab30ae88c5816335290b8e4d815c79b 100644
--- a/ash/mus/bridge/wm_shell_mus.cc
+++ b/ash/mus/bridge/wm_shell_mus.cc
@@ -242,6 +242,10 @@ bool WmShellMus::IsOverviewModeRestoringMinimizedWindows() {
   return false;
 }
 
+void WmShellMus::ToggleIgnoreExternalKeyboard() {
+  NOTIMPLEMENTED();
+}
+
 AccessibilityDelegate* WmShellMus::GetAccessibilityDelegate() {
   return accessibility_delegate_.get();
 }