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

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index 41d1cc9b050bdb5cb5e9300ab91a9a9a7270c3af..7fc8ef3b93c7e45c35e20a8f3a87e7499c56d366 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -403,6 +403,7 @@ void ApplyRenderParams(const FontRenderParams& params,
 RenderText::~RenderText() {
 }
 
+// static
 RenderText* RenderText::CreateInstance() {
 #if defined(OS_MACOSX)
   static const bool use_native =
@@ -414,6 +415,7 @@ RenderText* RenderText::CreateInstance() {
   return new RenderTextHarfBuzz;
 }
 
+// static
 RenderText* RenderText::CreateInstanceForEditing() {
   return new RenderTextHarfBuzz;
 }