alternate ntp (cros/partial-win): add tab-related stuff and toolbar/tab background change

chrome/browser/ui/search/toolbar_search_animator_observer.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_
+#define CHROME_BROWSER_UI_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_
+#pragma once
+
+class TabContents;
+
+namespace chrome {
+namespace search {
+
+// This class defines the observer interface for |ToolbarSearchAnimator|.
+class ToolbarSearchAnimatorObserver {
+ public:
+  // Called from ui::AnimationDelegate::AnimationProgressed.
+  virtual void OnToolbarBackgroundAnimatorProgressed() = 0;
+
+  // Called when animation is canceled and jumps to the end state.
+  // If animation is canceled because the active tab is deactivated or detached
+  // or closing, |tab_contents| contains the tab's contents.
+  // Otherwise, if animation is canceled because of mode change, |tab_contents|
+  // is NULL.
+  virtual void OnToolbarBackgroundAnimatorCanceled(
+      TabContents* tab_contents) = 0;

[sky, 2012/06/27 04:18:36]

The use of tab_contents here is confusing. Can you pass in an enum indicating
why the animation was canceled?

[kuan, 2012/06/27 10:29:52]

u mean ADD an enum like
ToolbarSearchAnimator::TAB_DEACTIVATED|TAB_DETACHED|TAB_CLOSING?
how should the observer use this enum?

BrowserTabStripObserver needs |tab_contents| to figure out the index of the
affected tab in the tab model so that the correct TabRendererData is updated, is
there another way?

[sky, 2012/06/27 14:11:44]

AH, I see. In that case I don't understand why you ever need to pass in NULL?

[kuan, 2012/06/27 16:38:14]

aha.. i'm embarrassed to say that's a bug on my part :(
|tab_contents| is NULL when animation is canceled because of mode change (as
commented above).  i was firing cancelation notification, BUT the observer
BrowserTabStripController wasn't doing anything 'cos |tab_contents| is NULL. :(
i have fixed this in BrowserTabStripController to get active index if
|tab_contents| is NULL, and verified it manually and visually.
While BrowserTabStripController does get ModeChanged like ToolbarSearchAnimator,
the order of which gets notification first is not gauranteed; if
BrowserTabStripController gets ModeChanged before ToolbarSearchAnimator does,
the state in ToolbarSearchAnimator is not updated.  so i need to fire a
cancelation notification to make sure observers update their states accordingly.

+
+ protected:
+  virtual ~ToolbarSearchAnimatorObserver() {}
+};
+
+}  // namespace search
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_SEARCH_TOOLBAR_SEARCH_ANIMATOR_OBSERVER_H_