Implement "Look Up In Dictionary" context menu item asynchronously.

content/browser/renderer_host/render_widget_host_view_mac.h

Index: content/browser/renderer_host/render_widget_host_view_mac.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index cc295afb950533e020ba0d391708a26ae1d6d7fb..2bab190b045df4d08ff8038950b6390774259f95 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -208,6 +208,7 @@ class Layer;
 - (void)updateCursor:(NSCursor*)cursor;
 - (NSRect)firstViewRectForCharacterRange:(NSRange)theRange
                              actualRange:(NSRangePointer)actualRange;
+- (void) ShowLookUpDictionary:(NSPoint)point;

[Alexei Svitkine (slow), 2015/09/01 16:27:03]

Nit: Use objc naming convention please.

e.g.

- (void)showLookUpDictionaryOverlayAtPoint:(NSPoint)point;

[Shu Chen, 2015/09/02 03:35:42]

Done.

 @end
 
 namespace content {
@@ -362,6 +363,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   void PluginImeCompositionCompleted(const base::string16& text, int plugin_id);
 
   const std::string& selected_text() const { return selected_text_; }
+  const gfx::Range& composition_range() const { return composition_range_; }
+  const base::string16& selection_text() const { return selection_text_; }
+  size_t selection_text_offset() const { return selection_text_offset_; }
 
   // Returns true and stores first rectangle for character range if the
   // requested |range| is already cached, otherwise returns false.
@@ -587,6 +591,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // The current caret bounds.
   gfx::Rect caret_rect_;
 
+  // The current first selection bounds.
+  gfx::Rect first_selection_rect_;
+
   // Factory used to safely scope delayed calls to ShutdownHost().
   base::WeakPtrFactory<RenderWidgetHostViewMac> weak_factory_;