ash: Update the volume icon when audio is muted/unmuted.

ash/system/audio/tray_volume.cc

 // Copyright (c) 2012 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/tray_volume.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "ash/system/tray/tray_constants.h"
 #include "base/utf_string_conversions.h"
@@ skipping 97 matching lines @@
     slider_ = new views::Slider(this, views::Slider::HORIZONTAL);
     slider_->SetValue(delegate->GetVolumeLevel());
     slider_->set_border(views::Border::CreateEmptyBorder(0, 0, 0, 20));
     AddChildView(slider_);
   }
 
   virtual ~VolumeView() {}
 
   void SetVolumeLevel(float percent) {
     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 a repaint. So explicitly trigger a repaint.
+    icon_->SchedulePaint();
   }
 
  private:
   // Overridden from views::ButtonListener.
   virtual void ButtonPressed(views::Button* sender,
                              const views::Event& event) OVERRIDE {
     CHECK(sender == icon_);
     ash::SystemTrayDelegate* delegate =
         ash::Shell::GetInstance()->tray_delegate();
     delegate->SetAudioMuted(!delegate->IsAudioMuted());
@@ skipping 52 matching lines @@
   if (volume_view_.get()) {
     volume_view_->SetVolumeLevel(percent);
     return;
   }
 
   PopupDetailedView(kTrayPopupAutoCloseDelayInSeconds, false);
 }
 
 }  // namespace internal
 }  // namespace ash