Implemented prototype for new ink drop specs.

chrome/browser/ui/views/toolbar/back_button.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/ui/views/toolbar/back_button.h"
 
 #include "ui/gfx/geometry/insets.h"
 #include "ui/views/animation/ink_drop_animation_controller.h"
 #include "ui/views/controls/button/label_button_border.h"
 #include "ui/views/painter.h"
@@ skipping 15 matching lines @@
   // probably a FocusBorder constant.
   const int kFocusRectInset = 3;
   SetFocusPainter(views::Painter::CreateDashedFocusPainterWithInsets(
                       gfx::Insets(kFocusRectInset, kFocusRectInset + margin,
                                   kFocusRectInset, kFocusRectInset)));
 
   InvalidateLayout();
 }
 
 void BackButton::LayoutInkDrop() {
-  ink_drop_animation_controller()->SetInkDropBounds(
-      gfx::Rect(margin_leading_, 0, width() - margin_leading_, height()));
+  ToolbarButton::LayoutInkDrop();

[Peter Kasting, 2015/09/03 21:53:06]

As a reader I'm unsure whether this line has to be before the next one (it
almost seems like it should be after the next one since I'd have thought setting
the ink drop center correctly would be something we'd need to do before
layout?).

Then we have the opposite ordering in ToolbarButton::NotifyClick(), where we
call the superclass method after messing with the animation controller.

If either of these places requires its current ordering, comment to that effect.
 Consider making the orderings match if possible.

[bruthig, 2015/09/09 18:00:35]

I've re-worked this a little bit. FTR the ordering in
ToolbarButton::NotifyClick() doesn't matter.

+  ink_drop_animation_controller()->SetInkDropCenter(gfx::Point(
+      (width() - margin_leading_) / 2 + margin_leading_, height() / 2));

[Peter Kasting, 2015/09/03 21:53:06]

Nit: Seems like you can just do (width() + margin_leading_) / 2

[bruthig, 2015/09/09 18:00:35]

Done.

 }
 
 const char* BackButton::GetClassName() const {
   return "BackButton";
 }
 
 scoped_ptr<views::LabelButtonBorder> BackButton::CreateDefaultBorder() const {
   scoped_ptr<views::LabelButtonBorder> border =
       ToolbarButton::CreateDefaultBorder();
 
   // Adjust border insets to follow the margin change,
   // which will be reflected in where the border is painted
   // through |GetThemePaintRect|.
   const gfx::Insets insets(border->GetInsets());
   border->set_insets(gfx::Insets(insets.top(), insets.left() + margin_leading_,
                                  insets.bottom(), insets.right()));
 
   return border.Pass();
 }
 
 gfx::Rect BackButton::GetThemePaintRect() const  {
   gfx::Rect rect(LabelButton::GetThemePaintRect());
   rect.Inset(margin_leading_, 0, 0, 0);
   return rect;
 }