Refactoring to make adding ink drop animations easier

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 0fc755972d6d57de055a7ea9d31fa11733eaf13b..6d94258797a3c46b7f86f669f76064581f83a73c 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -39,6 +39,7 @@
 #include "ui/gfx/transform.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/views/accessibility/native_view_accessibility.h"
+#include "ui/views/animation/ink_drop_delegate.h"
 #include "ui/views/background.h"
 #include "ui/views/border.h"
 #include "ui/views/context_menu_controller.h"
@@ -81,6 +82,28 @@ const View* GetHierarchyRoot(const View* view) {
   return root;
 }
 
+// A stub InkDropDelegate implementation that always exists and does nothing.
+// A real InkDropDelegate descendant can be returned by a View's descendant via
+// GetInkDropDelegate().
+class InkDropDelegateStub : public InkDropDelegate {
+ public:
+  InkDropDelegateStub() {}
+  ~InkDropDelegateStub() override {}
+
+  // InkDropDelegate:
+  void SetInkDropSize(int large_size,
+                      int large_corner_radius,
+                      int small_size,
+                      int small_corner_radius) override {}
+  void OnLayout() override {}
+  void OnAction(InkDropState state) override {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(InkDropDelegateStub);
+};
+
+static InkDropDelegateStub ink_drop_delegate_stub;
+
 }  // namespace
 
 // static
@@ -518,6 +541,8 @@ void View::Layout() {
       child->Layout();
     }
   }
+
+  GetInkDropDelegate()->OnLayout();
 }
 
 void View::InvalidateLayout() {
@@ -1254,6 +1279,7 @@ int View::OnPerformDrop(const ui::DropTargetEvent& event) {
 }
 
 void View::OnDragDone() {
+  GetInkDropDelegate()->OnAction(InkDropState::HIDDEN);
 }
 
 // static
@@ -1519,6 +1545,12 @@ void View::ReorderChildLayers(ui::Layer* parent_layer) {
   }
 }
 
+// Animations ----------------------------------------------------------------
+
+InkDropDelegate* View::GetInkDropDelegate() const {
+  return &ink_drop_delegate_stub;
+}
+
 // Input -----------------------------------------------------------------------
 
 View::DragInfo* View::GetDragInfo() {