Reduce the number of text reshaping in RenderText

ui/gfx/render_text_mac.h

Index: ui/gfx/render_text_mac.h
diff --git a/ui/gfx/render_text_mac.h b/ui/gfx/render_text_mac.h
index 5b33e00af0e885b313c8b8a7602945d53cb43606..fdd83cfe49ac7deacfe367df2b54daf0e97026a9 100644
--- a/ui/gfx/render_text_mac.h
+++ b/ui/gfx/render_text_mac.h
@@ -25,15 +25,16 @@ class RenderTextMac : public RenderText {
   RenderTextMac();
   ~RenderTextMac() override;
 
-  // Overridden from RenderText:
+  // RenderText:
   scoped_ptr<RenderText> CreateInstanceOfSameType() const override;
+  const base::string16& GetLayoutText() override;
   Size GetStringSize() override;
   SizeF GetStringSizeF() override;
   SelectionModel FindCursorPosition(const Point& point) override;
   std::vector<FontSpan> GetFontSpansForTesting() override;
 
  protected:
-  // Overridden from RenderText:
+  // RenderText:
   int GetLayoutTextBaseline() override;
   SelectionModel AdjacentCharSelectionModel(
       const SelectionModel& selection,
@@ -43,10 +44,11 @@ class RenderTextMac : public RenderText {
       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 TextIndexToLayoutIndex(size_t index) override;
+  size_t LayoutIndexToTextIndex(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;