Adds ability for pre-target accelerators to not consume events

ash/mus/window_manager.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/mus/window_manager.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 212 matching lines @@
     bool janky) {
   for (auto* window : client_windows)
     SetWindowIsJanky(window, janky);
 }
 
 void WindowManager::OnWmNewDisplay(::ui::Window* window,
                                    const display::Display& display) {
   CreateRootWindowController(window, display);
 }
 
-void WindowManager::OnAccelerator(uint32_t id, const ui::Event& event) {
-  switch (id) {
-    case kWindowSwitchAccelerator:
-      window_manager_client()->ActivateNextWindow();
-      break;
-    default:
-      FOR_EACH_OBSERVER(WindowManagerObserver, observers_,
-                        OnAccelerator(id, event));
-      break;
-  }
-}
-
 void WindowManager::OnWmPerformMoveLoop(
     ::ui::Window* window,
     ::ui::mojom::MoveLoopSource source,
     const gfx::Point& cursor_location,
     const base::Callback<void(bool)>& on_done) {
   NOTIMPLEMENTED();
 }
 
 void WindowManager::OnWmCancelMoveLoop(::ui::Window* window) {
   NOTIMPLEMENTED();
 }
 
+ui::mojom::EventResult WindowManager::OnAccelerator(uint32_t id,
+                                                    const ui::Event& event) {
+  switch (id) {
+    case kWindowSwitchAccelerator:
+      window_manager_client()->ActivateNextWindow();
+      break;
+    default:
+      FOR_EACH_OBSERVER(WindowManagerObserver, observers_,
+                        OnAccelerator(id, event));
+      break;
+  }
+  return ui::mojom::EventResult::HANDLED;
+}
+
 }  // namespace mus
 }  // namespace ash