Views:: Make Labels support text selection.

ui/gfx/render_text.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_RENDER_TEXT_H_
 #define UI_GFX_RENDER_TEXT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 445 matching lines @@
   virtual SelectionModel FindCursorPosition(const Point& point) = 0;
 
   // Returns true if the position is a valid logical index into text(), and is
   // also a valid grapheme boundary, which may be used as a cursor position.
   virtual bool IsValidCursorIndex(size_t index) = 0;
 
   // Returns true if the position is a valid logical index into text(). Indices
   // amid multi-character graphemes are allowed here, unlike IsValidCursorIndex.
   virtual bool IsValidLogicalIndex(size_t index) const;
 
+  // Returns true if this instance supports text selection.
+  virtual bool IsSelectionSupported() const = 0;
+
   // Get the visual bounds of a cursor at |caret|. These bounds typically
   // represent a vertical line if |insert_mode| is true. Pass false for
   // |insert_mode| to retrieve the bounds of the associated glyph. These bounds
   // are in local coordinates, but may be outside the visible region if the text
   // is longer than the textfield. Subsequent text, cursor, or bounds changes
   // may invalidate returned values. Note that |caret| must be placed at
   // grapheme boundary, i.e. caret.caret_pos() must be a cursorable position.
   Rect GetCursorBounds(const SelectionModel& caret, bool insert_mode);
 
   // Compute the current cursor bounds, panning the text to show the cursor in
@@ skipping 382 matching lines @@
   // Lines computed by EnsureLayout. These should be invalidated upon
   // OnLayoutTextAttributeChanged and OnDisplayTextAttributeChanged calls.
   std::vector<internal::Line> lines_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderText);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_H_