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

content/browser/renderer_host/text_input_client_mac.h

Index: content/browser/renderer_host/text_input_client_mac.h
diff --git a/content/browser/renderer_host/text_input_client_mac.h b/content/browser/renderer_host/text_input_client_mac.h
index 4e50eff5c7e39c0fc8e9227154c945ba16aa5bce..7bf9fd00ef8d8f5b89fb403d9d7a5607e1298708 100644
--- a/content/browser/renderer_host/text_input_client_mac.h
+++ b/content/browser/renderer_host/text_input_client_mac.h
@@ -66,7 +66,6 @@ class CONTENT_EXPORT TextInputClientMac {
   // allow the Get*() methods to continue/return.
   void SetCharacterIndexAndSignal(NSUInteger index);
   void SetFirstRectAndSignal(NSRect first_rect);
-  void SetSubstringAndSignal(NSAttributedString* string);
 
   // This async method is invoked from RenderWidgetHostViewCocoa's
   // -quickLookWithEvent:, when the user taps a word using 3 fingers.
@@ -97,7 +96,6 @@ class CONTENT_EXPORT TextInputClientMac {
 
   NSUInteger character_index_;
   NSRect first_rect_;
-  base::scoped_nsobject<NSAttributedString> substring_;
 
   base::Lock lock_;
   base::ConditionVariable condition_;