Fix shelf auto-hide calculation for app-list visibility.

ash/common/shelf/app_list_button.h

Index: ash/common/shelf/app_list_button.h
diff --git a/ash/common/shelf/app_list_button.h b/ash/common/shelf/app_list_button.h
index fad5bbeb9a16d254279f7c32fb6ef22bfb0c7962..24159a0cdb7b34092a4785e2aefb97692c98b41c 100644
--- a/ash/common/shelf/app_list_button.h
+++ b/ash/common/shelf/app_list_button.h
@@ -25,7 +25,9 @@ class ASH_EXPORT AppListButton : public views::ImageButton {
   void OnAppListShown();
   void OnAppListDismissed();
 
-  bool draw_background_as_active() { return draw_background_as_active_; }
+  bool is_showing_app_list() const { return is_showing_app_list_; }
+
+  bool draw_background_as_active() const { return draw_background_as_active_; }
 
   // Sets alpha value of the background and schedules a paint.
   void SetBackgroundAlpha(int alpha);
@@ -63,12 +65,15 @@ class ASH_EXPORT AppListButton : public views::ImageButton {
   // ink drops.
   gfx::Point GetCenterPoint() const;
 
+  // True if the app list is currently showing for this button.

[James Cook, 2016/12/01 02:02:07]

nit: button/display (since the fact that this is per-display is important). You
might also comment that this is different from WmShell::IsApplistVisible().

Basically, it's weird that we can't use WmShell::IsApplistVisible() so it would
be nice to say something about that somewhere.

[msw, 2016/12/01 04:18:13]

Done.

+  bool is_showing_app_list_ = false;

[James Cook, 2016/12/01 02:02:07]

nit: I prefer to either initialize all members in the header or all members in
the .cc file. In this case, it looks like they will all need to go in .cc since
some of them are constructed.

[msw, 2016/12/01 04:18:13]

Done.

+
   // True if the background should render as active, regardless of the state of
   // the application list.
-  bool draw_background_as_active_;
+  bool draw_background_as_active_ = false;
 
   // Alpha value used to paint the background.
-  int background_alpha_;
+  int background_alpha_ = 0;
 
   InkDropButtonListener* listener_;
   ShelfView* shelf_view_;