Cache gfx::RenderText instances in views::Label.

ui/gfx/render_text.h

Index: ui/gfx/render_text.h
diff --git a/ui/gfx/render_text.h b/ui/gfx/render_text.h
index 4d629a00a0479cefddad8a86a0d5b453e9941288..bc9a6b67756186a34d785546b3cd6c8d37d74fc9 100644
--- a/ui/gfx/render_text.h
+++ b/ui/gfx/render_text.h
@@ -256,6 +256,9 @@ class GFX_EXPORT RenderText {
   bool multiline() const { return multiline_; }
   void SetMultiline(bool multiline);
 
+  // Returns true if this instance supports multiline rendering.
+  virtual bool MultilineSupported() const = 0;
+
   // TODO(ckocagil): Add vertical alignment and line spacing support instead.
   int min_line_height() const { return min_line_height_; }
   void SetMinLineHeight(int line_height);
@@ -266,7 +269,7 @@ class GFX_EXPORT RenderText {
   // WARNING: Only use this for system limits, it lacks complex text support.
   void set_truncate_length(size_t length) { truncate_length_ = length; }
 
-  // The layout text will be elided to fit |display_rect| using this behavior.
+  // The display text will be elided to fit |display_rect| using this behavior.
   void SetElideBehavior(ElideBehavior elide_behavior);
   ElideBehavior elide_behavior() const { return elide_behavior_; }
 
@@ -428,7 +431,7 @@ class GFX_EXPORT RenderText {
 
   // Sets shadows to drawn with text.
   void set_shadows(const ShadowValues& shadows) { shadows_ = shadows; }
-  const ShadowValues& shadows() { return shadows_; }
+  const ShadowValues& shadows() const { return shadows_; }
 
   typedef std::pair<Font, Range> FontSpan;
   // For testing purposes, returns which fonts were chosen for which parts of