Added notification when user presses backspace to use new shortcut.

chrome/browser/ui/views/backspace_new_shortcut_bubble.h

+// Copyright 2016 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_BACKSPACE_NEW_SHORTCUT_BUBBLE_H_
+#define CHROME_BROWSER_UI_VIEWS_BACKSPACE_NEW_SHORTCUT_BUBBLE_H_
+
+#include <memory>
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "base/timer/timer.h"
+#include "ui/gfx/animation/animation_delegate.h"
+
+class ExclusiveAccessBubbleViewsContext;
+class SubtleNotificationView;
+
+namespace gfx {
+class Animation;
+class Rect;
+class SlideAnimation;
+}
+
+namespace views {
+class View;
+class Widget;
+}
+
+// BackspaceNewShortcutBubble shows a short-lived notification along the top of
+// the screen when the user presses the old Back/Forward shortcut, telling them
+// how to use the new shortcut. This will only be available for a few milestones
+// to let users adapt.
+// TODO(mgiuca): Remove this in M54 (https://crbug.com/610039).
+class BackspaceNewShortcutBubble : public gfx::AnimationDelegate {

[Peter Kasting, 2016/05/19 10:08:37]

Can any of this class be combined with/factored out of ExclusiveAccessBubble?

[Matt Giuca, 2016/05/23 04:22:57]

Probably a little bit (setting up / tearing down the widget, some of the bounds
updating stuff).

I think given that we are past branch point, we don't want to do a significant
refactor of ExclusiveAccessBubbleViews, especially since this code is fairly
small and temporary. I already did a huuuge refactor of ExclusiveAccessBubble to
factor out SubtleNotificationView so I think this amount of code duplication is
a good balance.

+ public:
+  BackspaceNewShortcutBubble(ExclusiveAccessBubbleViewsContext* context,
+                             bool forward);
+  ~BackspaceNewShortcutBubble() override;
+
+  void UpdateContent(bool forward);
+
+ private:
+  // Updates |popup|'s bounds given |animation_| and |animated_attribute_|.

[Peter Kasting, 2016/05/19 10:08:36]

Nit: popup -> popup_ ; there is no member animated_attribute_.

[Matt Giuca, 2016/05/23 04:22:57]

Gone.

+  void UpdateBounds();
+
+  void UpdateViewContent(bool forward);
+
+  // Returns the root view containing |browser_view_|.
+  views::View* GetBrowserRootView() const;

[Peter Kasting, 2016/05/19 10:08:36]

Nit: Const functions should not return non-const pointers; make the pointer
const or the function non-const.

[Matt Giuca, 2016/05/23 04:22:57]

Gone.

+
+  // gfx::AnimationDelegate overrides:

[Peter Kasting, 2016/05/19 10:08:37]

Nit: Place overrides above or below all non-overrides (I generally do above).

No need for the word "overrides" in this comment.

[Matt Giuca, 2016/05/23 04:22:57]

Done.

+  void AnimationProgressed(const gfx::Animation* animation) override;
+  void AnimationEnded(const gfx::Animation* animation) override;
+
+  gfx::Rect GetPopupRect(bool ignore_animation_state) const;
+  void Hide();
+  void Show();
+  void TimerElapsed();

[Peter Kasting, 2016/05/19 10:08:37]

Nit: OnTimerElapsed()?

[Matt Giuca, 2016/05/23 04:22:57]

Done.

+
+  ExclusiveAccessBubbleViewsContext* const bubble_view_context_;
+
+  views::Widget* popup_;
+
+  // Animation controlling showing/hiding of the exit bubble.

[Peter Kasting, 2016/05/19 10:08:37]

Nit: This isn't an "exit" bubble.

[Matt Giuca, 2016/05/23 04:22:57]

Done.

+  std::unique_ptr<gfx::SlideAnimation> animation_;
+
+  // Timer before the bubble disappears.
+  base::OneShotTimer hide_timeout_;
+
+  // The contents of the popup.
+  SubtleNotificationView* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(BackspaceNewShortcutBubble);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_BACKSPACE_NEW_SHORTCUT_BUBBLE_H_