Implemented prototype for new ink drop specs.

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

Index: chrome/browser/ui/views/toolbar/back_button.cc
diff --git a/chrome/browser/ui/views/toolbar/back_button.cc b/chrome/browser/ui/views/toolbar/back_button.cc
index 73ae0411c64c06f374cbaab0be52536da6b57451..eaf4310c698b258b2014f968f45ec798603b5106 100644
--- a/chrome/browser/ui/views/toolbar/back_button.cc
+++ b/chrome/browser/ui/views/toolbar/back_button.cc
@@ -33,8 +33,9 @@ void BackButton::SetLeadingMargin(int margin) {
 }
 
 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 {