Added the Material Design ink drop ripple effect to the navigation buttons in the browser toolbar.

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

Index: chrome/browser/ui/views/toolbar/toolbar_button.cc
diff --git a/chrome/browser/ui/views/toolbar/toolbar_button.cc b/chrome/browser/ui/views/toolbar/toolbar_button.cc
index cf2e626384f1695631238f10ba4d0867ef99b4f4..6b6e35f099d8b703a2fcdc69d2a7b816ad6e777c 100644
--- a/chrome/browser/ui/views/toolbar/toolbar_button.cc
+++ b/chrome/browser/ui/views/toolbar/toolbar_button.cc
@@ -18,6 +18,7 @@
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
 #include "ui/strings/grit/ui_strings.h"
+#include "ui/views/animation/ink_drop_animation_controller.h"
 #include "ui/views/controls/button/label_button_border.h"
 #include "ui/views/controls/menu/menu_item_view.h"
 #include "ui/views/controls/menu/menu_model_adapter.h"
@@ -31,6 +32,18 @@ ToolbarButton::ToolbarButton(views::ButtonListener* listener,
       menu_showing_(false),
       y_position_on_lbuttondown_(0),
       show_menu_factory_(this) {
+#if defined(OS_CHROMEOS)
+  // The ink drop animation is only targeted at ChromeOS because there is
+  // concern it will conflict with OS level touch feedback in a bad way.
+  if (ui::MaterialDesignController::IsModeMaterial()) {
+    ink_drop_animation_controller_.reset(
+        new views::InkDropAnimationController(this));
+    layer()->SetFillsBoundsOpaquely(false);
+    image()->SetPaintToLayer(true);
+    image()->SetFillsBoundsOpaquely(false);
+  }
+#endif  // defined(OS_CHROMEOS)
+
   set_context_menu_controller(this);
 }
 
@@ -148,6 +161,21 @@ ToolbarButton::CreateDefaultBorder() const {
   scoped_ptr<views::LabelButtonBorder> border =
       LabelButton::CreateDefaultBorder();
 
+  if (ui::MaterialDesignController::IsModeMaterial()) {
+    // The material design spec does not include a visual effect for the
+    // STATE_HOVERED button state so we have to remove the default one added by
+    // LabelButton::CreateDefaultBorder().
+    border->SetPainter(true, Button::STATE_HOVERED, nullptr);
+    border->SetPainter(false, Button::STATE_HOVERED, nullptr);
+
+#if defined(OS_CHROMEOS)
+    // The default STATE_PRESSED painters need to be removed so that they do not
+    // conflict with the ink drop ripple effect.
+    border->SetPainter(true, Button::STATE_PRESSED, nullptr);

[Evan Stade, 2015/07/22 16:29:46]

for my edification, is it intentional that this also removes the pressed state
for pointer events, even though the inkdrop only works for touch events? (Is the
inkdrop going to work with pointer events as well?)

+    border->SetPainter(false, Button::STATE_PRESSED, nullptr);
+#endif  // defined(OS_CHROMEOS)
+  }
+
   ui::ThemeProvider* provider = GetThemeProvider();
   if (provider && provider->UsingSystemTheme()) {
     // Theme provided insets.