Add MD ink drop ripple to app list button

ui/views/animation/ink_drop_host_view.h

Index: ui/views/animation/ink_drop_host_view.h
diff --git a/ui/views/animation/ink_drop_host_view.h b/ui/views/animation/ink_drop_host_view.h
index 030faa810d10a889f644f2e14113771b12b4f14a..440fed4436b98b85ccaaf4de7729ce46014fed3d 100644
--- a/ui/views/animation/ink_drop_host_view.h
+++ b/ui/views/animation/ink_drop_host_view.h
@@ -38,6 +38,16 @@ class VIEWS_EXPORT InkDropHostView : public View, public InkDropHost {
   void set_ink_drop_size(const gfx::Size& size) { ink_drop_size_ = size; }
 
  protected:
+  // Used in SetInkDropMode() to specify whether the ink drop effect is enabled
+  // or not for the view. In case of having an ink drop, it also specifies
+  // whether the default gesture event handler for the ink drop should be
+  // installed or the subclass will handle gesture events itself.
+  enum InkDropMode {
+    NO_INK_DROP,
+    INK_DROP_WITHOUT_GESTURE_HANDLING,
+    INK_DROP_WITH_GESTURE_HANDLING,

[sky, 2016/06/30 00:35:34]

Sorry, one concern I have in looking at the changes to supporting code is that
it isn't clear why any of the code wants gesture handling. My concern is just
the naming, I think if INK_DROP_WITHOUT_GESTURE_HANDLING was named INK_DROP_ON
(or InkDropMode::ON) it would be easier to understand and
InkDropMode::ON_NO_GESTURE_HANDLER for the outliers.
Another option is to keep the boolean and instead have an explicit
SetIsGestureHandlingEnabled() to turn on/off the gesture handling. I actually
might go for that. WDYT?

[mohsen, 2016/06/30 08:54:07]

Having two separate functions makes the code a bit complicated. First,
SetIsGestureHandlingEnabled() is not meaningful if ink drop is not enabled.
Second, they can probably be called in any order which might be unnecessarily
difficult to handle; especially that currently the difference between ink drop
being enabled vs. disabled is having an instance of InkDropImpl vs. InkDropStub.
This default gesture handler is also something that we are considering getting
rid of (see TODO above its definition in ink_drop_host_view.cc). All in all, I
think this approach is not worth its complexity. So, I opted for your first
suggestion of renaming enum values to OFF, ON, ON_NO_GESTURE_HANDLER.

+  };
+
   static const int kInkDropSmallCornerRadius;
 
   void set_ink_drop_visible_opacity(float visible_opacity) {
@@ -84,7 +94,7 @@ class VIEWS_EXPORT InkDropHostView : public View, public InkDropHost {
   // Toggle to enable/disable an InkDrop on this View.  Descendants can override
   // CreateInkDropHighlight() and CreateInkDropRipple() to change the look/feel
   // of the InkDrop.
-  void SetHasInkDrop(bool has_an_ink_drop);
+  void SetInkDropMode(InkDropMode ink_drop_mode);
 
  private:
   class InkDropGestureHandler;