Reduce the number of text reshaping in RenderText

ui/gfx/render_text_mac.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_MAC_H_
 #define UI_GFX_RENDER_TEXT_MAC_H_
 
 #include <ApplicationServices/ApplicationServices.h>
 
 #include <string>
 #include <vector>
 
 #include "base/mac/scoped_cftyperef.h"
 #include "ui/gfx/render_text.h"
 
 namespace gfx {
 
 // RenderTextMac is the Mac implementation of RenderText that uses CoreText for
 // layout and Skia for drawing.
 //
 // Note: The current implementation only supports drawing and sizing the text,
 //       but not text selection or cursor movement.
 class RenderTextMac : public RenderText {
  public:
   RenderTextMac();
   ~RenderTextMac() override;
 
-  // Overridden from RenderText:
+  // RenderText:
   scoped_ptr<RenderText> CreateInstanceOfSameType() const override;
+  const base::string16& GetDisplayText() override;
   Size GetStringSize() override;
   SizeF GetStringSizeF() override;
   SelectionModel FindCursorPosition(const Point& point) override;
   std::vector<FontSpan> GetFontSpansForTesting() override;
 
  protected:
-  // Overridden from RenderText:
-  int GetLayoutTextBaseline() override;
+  // RenderText:
+  int GetDisplayTextBaseline() override;
   SelectionModel AdjacentCharSelectionModel(
       const SelectionModel& selection,
       VisualCursorDirection direction) override;
   SelectionModel AdjacentWordSelectionModel(
       const SelectionModel& selection,
       VisualCursorDirection direction) override;
   Range GetGlyphBounds(size_t index) override;
   std::vector<Rect> GetSubstringBounds(const Range& range) override;
-  size_t TextIndexToLayoutIndex(size_t index) const override;
-  size_t LayoutIndexToTextIndex(size_t index) const override;
+  size_t TextIndexToDisplayIndex(size_t index) override;
+  size_t DisplayIndexToTextIndex(size_t index) override;
   bool IsValidCursorIndex(size_t index) override;
-  void ResetLayout() override;
+  void OnLayoutTextAttributeChanged(bool text_changed) override;
+  void OnDisplayTextAttributeChanged() override;
   void EnsureLayout() override;
   void DrawVisualText(Canvas* canvas) override;
 
  private:
   struct TextRun {
     CTRunRef ct_run;
     SkPoint origin;
     std::vector<uint16> glyphs;
     std::vector<SkPoint> glyph_positions;
     SkScalar width;
@@ skipping 34 matching lines @@
 
   // Indicates that |runs_| are valid, set by |ComputeRuns()|.
   bool runs_valid_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderTextMac);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_MAC_H_