Merge to m48: Fix volume slider to emit value changed events and do not focus system tray it\

ash/system/audio/volume_view.cc

 // Copyright 2014 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/system/audio/volume_view.h"
 
 #include "ash/ash_constants.h"
 #include "ash/shell.h"
 #include "ash/system/audio/tray_audio.h"
 #include "ash/system/audio/tray_audio_delegate.h"
@@ skipping 157 matching lines @@
   Layout();
 }
 
 void VolumeView::SetVolumeLevel(float percent) {
   // Slider's value is in finer granularity than audio volume level(0.01),
   // there will be a small discrepancy between slider's value and volume level
   // on audio side. To avoid the jittering in slider UI, do not set change
   // slider value if the change is less than 1%.
   if (std::abs(percent-slider_->value()) < 0.01)
     return;
-  // The change in volume will be reflected via accessibility system events,
-  // so we prevent the UI event from being sent here.
-  slider_->set_enable_accessibility_events(false);
   slider_->SetValue(percent);
   // It is possible that the volume was (un)muted, but the actual volume level
   // did not change. In that case, setting the value of the slider won't
   // trigger an update. So explicitly trigger an update.
   Update();
   slider_->set_enable_accessibility_events(true);
 }
 
 void VolumeView::UpdateDeviceTypeAndMore() {
   bool show_more = is_default_view_ && TrayAudio::ShowAudioDeviceMenu() &&
@@ skipping 85 matching lines @@
 
 void VolumeView::OnBoundsChanged(const gfx::Rect& previous_bounds) {
   // Separator's prefered size is based on set bounds. When an empty bounds is
   // set on first layout this causes BoxLayout to ignore the separator. Reset
   // its height on each bounds change so that it is laid out properly.
   separator_->SetSize(gfx::Size(kSeparatorSize, bounds().height()));
 }
 
 }  // namespace tray
 }  // namespace ash