Color the ink drop ripple and hover effects based on theming.

ui/views/controls/button/custom_button.cc

Index: ui/views/controls/button/custom_button.cc
diff --git a/ui/views/controls/button/custom_button.cc b/ui/views/controls/button/custom_button.cc
index 7f721a5f8a3d1a133cf3e8b89321cdb07ff95938..13e8893396c9e02df44ab703469da00b218b095a 100644
--- a/ui/views/controls/button/custom_button.cc
+++ b/ui/views/controls/button/custom_button.cc
@@ -9,6 +9,7 @@
 #include "ui/events/event_utils.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "ui/gfx/animation/throb_animation.h"
+#include "ui/gfx/color_palette.h"
 #include "ui/gfx/screen.h"
 #include "ui/views/animation/ink_drop_delegate.h"
 #include "ui/views/controls/button/blue_button.h"
@@ -367,6 +368,10 @@ bool CustomButton::ShouldShowInkDropHover() const {
   return enabled() && IsMouseHovered() && !InDrag();
 }
 
+SkColor CustomButton::GetInkDropBaseColor() const {
+  return ink_drop_base_color_;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // CustomButton, protected:
 
@@ -381,7 +386,8 @@ CustomButton::CustomButton(ButtonListener* listener)
       ink_drop_delegate_(nullptr),
       notify_action_(NOTIFY_ON_RELEASE),
       has_ink_drop_action_on_click_(false),
-      ink_drop_action_on_click_(InkDropState::QUICK_ACTION) {
+      ink_drop_action_on_click_(InkDropState::QUICK_ACTION),
+      ink_drop_base_color_(gfx::kPlaceholderColor) {
   hover_animation_.SetSlideDuration(kHoverFadeDurationMs);
 }