Tab audio mute control (views UI), behind a switch (off by default).

chrome/browser/ui/views/tabs/media_indicator_button.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_VIEWS_TABS_MEDIA_INDICATOR_BUTTON_H_
+#define CHROME_BROWSER_UI_VIEWS_TABS_MEDIA_INDICATOR_BUTTON_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/ui/tabs/tab_utils.h"
+#include "ui/views/controls/button/image_button.h"
+#include "ui/views/view_targeter_delegate.h"
+
+namespace gfx {
+class Animation;
+class AnimationDelegate;
+}
+
+// This is an ImageButton subclass that serves as both the media indicator icon
+// (audio, tab capture, etc.), and as a mute button.  It is meant to only be
+// used as a child view of Tab.
+//
+// When the indicator is transitioned to the audio playing or muting state, the
+// button functionality is enabled and begins handling mouse events.  Otherwise,
+// this view behaves like an image and all mouse events will be handled by the
+// Tab (its parent View).
+class MediaIndicatorButton : public views::ImageButton,
+                             public views::ViewTargeterDelegate {
+ public:
+  MediaIndicatorButton();
+  virtual ~MediaIndicatorButton();
+
+  // Returns the current TabMediaState except, while the indicator image is
+  // fading out, returns the prior TabMediaState.
+  TabMediaState showing_media_state() const {
+    return showing_media_state_;
+  }
+
+  // Updates ImageButton images, starts fade animations, and
+  // activates/deactivates button functionality as appropriate.
+  void TransitionToMediaState(TabMediaState next_state);
+
+  static const char kViewClassName[];

[sky, 2014/09/25 19:25:05]

nit: this should be first in the section (see style guide).

[miu, 2014/09/25 22:49:36]

Done.

+
+ protected:
+  // views::View:
+  virtual const char* GetClassName() const OVERRIDE;
+  virtual View* GetTooltipHandlerForPoint(const gfx::Point& point) OVERRIDE;
+  virtual bool OnMouseDragged(const ui::MouseEvent& event) OVERRIDE;
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+
+  // views::ViewTargeterDelegate
+  virtual bool DoesIntersectRect(const View* target,
+                                 const gfx::Rect& rect) const OVERRIDE;
+
+  // views::Button:
+  virtual void NotifyClick(const ui::Event& event) OVERRIDE;
+
+ private:
+  class FadeAnimationDelegate;
+
+  TabMediaState media_state_;
+
+  // Media indicator fade-in/out animation (i.e., only on show/hide, not a
+  // continuous animation).
+  scoped_ptr<gfx::AnimationDelegate> fade_animation_delegate_;
+  scoped_ptr<gfx::Animation> fade_animation_;
+  TabMediaState showing_media_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaIndicatorButton);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_TABS_MEDIA_INDICATOR_BUTTON_H_