Added a11y alert on entering overview mode

ash/wm/overview/window_overview.cc

 // Copyright 2013 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/wm/overview/window_overview.h"
 
 #include <algorithm>
 
+#include "ash/accessibility_delegate.h"
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/switchable_windows.h"
 #include "ash/wm/overview/scoped_transform_overview_window.h"
 #include "ash/wm/overview/window_selector.h"
 #include "ash/wm/overview/window_selector_item.h"
 #include "base/metrics/histogram.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ skipping 124 matching lines @@
     // TODO(flackr): Only prevent cursor changes for windows in the overview.
     // This will be easier to do without exposing the overview mode code if the
     // cursor changes are moved to ToplevelWindowEventHandler::HandleMouseMoved
     // as suggested there.
     cursor_client_->LockCursor();
   }
   shell->PrependPreTargetHandler(this);
   shell->GetScreen()->AddObserver(this);
   shell->metrics()->RecordUserMetricsAction(UMA_WINDOW_OVERVIEW);
   HideAndTrackNonOverviewWindows();
+  // Send an a11y alert only if the overview was activated by the user.
+  if (window_selector_->mode() == WindowSelector::OVERVIEW)

[flackr, 2014/04/29 14:21:16]

nit: need braces { } since the code block is multiple lines.

[Nina, 2014/04/29 14:24:34]

Done.

+    shell->accessibility_delegate()->TriggerAccessibilityAlert(
+        A11Y_ALERT_WINDOW_OVERVIEW_MODE_ENTERED);
 }
 
 WindowOverview::~WindowOverview() {
   const aura::WindowTracker::Windows hidden_windows = hidden_windows_.windows();
   for (aura::WindowTracker::Windows::const_iterator iter =
        hidden_windows.begin(); iter != hidden_windows.end(); ++iter) {
     ui::ScopedLayerAnimationSettings settings(
         (*iter)->layer()->GetAnimator());
     settings.SetTransitionDuration(base::TimeDelta::FromMilliseconds(
         ScopedTransformOverviewWindow::kTransitionMilliseconds));
@@ skipping 305 matching lines @@
 }
 
 gfx::Rect WindowOverview::GetSelectionBounds(size_t index) {
   gfx::Rect bounds((*windows_)[index]->bounds());
   bounds.Inset(-kWindowOverviewSelectionPadding,
                -kWindowOverviewSelectionPadding);
   return bounds;
 }
 
 }  // namespace ash