Do not activate system tray bubble by default

ash/common/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/common/system/audio/volume_view.h"
 
 #include "ash/common/ash_constants.h"
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/metrics/user_metrics_action.h"
 #include "ash/common/system/audio/tray_audio.h"
@@ skipping 105 matching lines @@
   system::TrayAudioDelegate* audio_delegate_;
   gfx::Image image_;
   int image_index_;
 
   DISALLOW_COPY_AND_ASSIGN(VolumeButton);
 };
 
 VolumeView::VolumeView(SystemTrayItem* owner,
                        system::TrayAudioDelegate* audio_delegate,
                        bool is_default_view)
-    : owner_(owner),
+    : ActionableView(owner),
       audio_delegate_(audio_delegate),
       icon_(NULL),
       slider_(NULL),
       device_type_(NULL),
       more_(NULL),
       is_default_view_(is_default_view) {
   SetFocusBehavior(FocusBehavior::NEVER);
   views::BoxLayout* box_layout = new views::BoxLayout(
       views::BoxLayout::kHorizontal, 0, 0, kBoxLayoutPadding);
   box_layout->SetDefaultFlex(0);
@@ skipping 157 matching lines @@
       HandleVolumeUp(new_volume);
     else
       HandleVolumeDown(new_volume);
   }
   icon_->Update();
 }
 
 bool VolumeView::PerformAction(const ui::Event& event) {
   if (!more_region_->visible())
     return false;
-  owner_->TransitionDetailedView();
+  owner()->TransitionDetailedView();
   return true;
 }
 
 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()));
 }
 
 void VolumeView::GetAccessibleState(ui::AXViewState* state) {
   // Intentionally overrides ActionableView, leaving |state| unset. A slider
   // childview exposes accessibility data.
 }
 
 }  // namespace tray
 }  // namespace ash