Implement double/triple click functionality in views textfield.

views/controls/textfield/textfield_views_model.h

Index: views/controls/textfield/textfield_views_model.h
diff --git a/views/controls/textfield/textfield_views_model.h b/views/controls/textfield/textfield_views_model.h
index a87157a37a0dfe79d7f572d9059dec7da3041af0..bcdc6bc8d3f3d943735e7c1848459590d08bee14 100644
--- a/views/controls/textfield/textfield_views_model.h
+++ b/views/controls/textfield/textfield_views_model.h
@@ -123,6 +123,9 @@ class TextfieldViewsModel {
   // Selects all text.
   void SelectAll();
 
+  // Selects the word at which the cursor is currently positioned.
+  void SelectWord();
+
   // Clears selection.
   void ClearSelection();
 
@@ -155,6 +158,9 @@ class TextfieldViewsModel {
   // Returns the visible text given |start| and |end|.
   string16 GetVisibleText(size_t start, size_t end) const;
 
+  // Utility for SelectWord(). Checks whether position pos is at word boundary.
+  bool IsPositionAtWordSelectionBoundary(size_t pos);
+
   // Returns the normalized cursor position that does not exceed the
   // text length.
   size_t GetSafePosition(size_t position) const;