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..aa903d99ae0c35576acccad8189ee3452a4413ef 100644
--- a/ui/views/view.h
+++ b/ui/views/view.h
@@ -49,6 +49,7 @@ namespace gfx {
 class Canvas;
 class Insets;
 class Path;
+class RenderText;
 class Transform;
 }
 
@@ -573,6 +574,11 @@ class VIEWS_EXPORT View : public ui::LayerDelegate,
   // NULL.
   virtual View* GetTooltipHandlerForPoint(const gfx::Point& point);
 
+  // Returns the RenderText instance corresponding to the view. Currently, only
+  // views which have at most one RenderText instance, should implement this.
+  virtual const gfx::RenderText* GetRenderText() const;

[sky, 2016/09/26 16:20:18]

Can you outline why this needs to be exposed on View? I would prefer consumers
that need to know the type of View they have and operate on it.

[karandeepb, 2016/09/27 01:09:11]

So the problem we want to solve is given a views::View, get the word being
displayed at some given point. This is only needed for Textfields and Labels
currently. Possible approaches-
1) Expose GetRenderText on View.
2) Expose GetWordAtPoint on View. (Subsequently we might also need something
like GetWordForRange).
3) Expose GetTextInputClient on View and add GetWordAtPoint to the
TextInputClient interface. (But Labels don't implement the TextInputClient
interface).
4) Use RTTI at the call site (BridgedContentView) with the help of
View::GetClassName() and static_cast.

I have also outlined these options on the linked doc -
https://docs.google.com/document/d/17QYrMpIXpk-FpGanjhJ-Yx33njNQy7B5oL_bxb7-v...

+  gfx::RenderText* GetRenderText();
+
   // Return the cursor that should be used for this view or the default cursor.
   // The event location is in the receiver's coordinate system. The caller is
   // responsible for managing the lifetime of the returned object, though that