MacViews: Implement Force Touch/Mac dictionary lookup for Textfields.

ui/views/view.h

Index: ui/views/view.h
diff --git a/ui/views/view.h b/ui/views/view.h
index 55cc02bb54da4eaa205df9f8adc17d5f84245279..57da2b0d35827b123d1ff39ccc57b2e9dd686456 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -73,6 +73,7 @@ class DragController;
 class FocusManager;
 class FocusTraversable;
 class LayoutManager;
+class LookupWordClient;
 class NativeViewAccessibility;
 class ScrollView;
 class Widget;
@@ -717,6 +718,9 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
 
   ViewTargeter* targeter() const { return targeter_.get(); }
 
+  // Returns the LookupWordClient associated with this view.
+  virtual LookupWordClient* GetLookupWordClient();
+
   // Overridden from ui::EventTarget:
   bool CanAcceptEvent(const ui::Event& event) override;
   ui::EventTarget* GetParentTarget() override;