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 c4f841dfcf7898f4b590f31839f865e8afbdac74..66d3ba781d0f25481e63a873dc2d778722fda680 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -402,6 +402,7 @@ void ApplyRenderParams(const FontRenderParams& params,
 RenderText::~RenderText() {
 }
 
+// static
 RenderText* RenderText::CreateInstance() {
 #if defined(OS_MACOSX)
   static const bool use_native =
@@ -413,6 +414,7 @@ RenderText* RenderText::CreateInstance() {
   return new RenderTextHarfBuzz;
 }
 
+// static
 RenderText* RenderText::CreateInstanceForEditing() {
   return new RenderTextHarfBuzz;
 }
@@ -717,6 +719,10 @@ VisualCursorDirection RenderText::GetVisualDirectionOfLogicalEnd() {
       CURSOR_RIGHT : CURSOR_LEFT;
 }
 
+const base::string16& RenderText::GetAccessibleText() {
+  return layout_text_;

[msw, 2015/02/25 23:54:26]

I think this should work as-is, since |layout_text_| is updated immediately on
each call to OnTextAttributeChanged, but I'm CC'ing oshima just in case, as per
the header comment for layout_text():
  // NOTE: The value of these accessors may be stale. Please make sure
  // that these fields are up-to-date before accessing them.

[Jun Mukai, 2015/02/26 01:40:24]

This method was removed.

+}
+
 SizeF RenderText::GetStringSizeF() {
   return GetStringSize();
 }
@@ -1093,7 +1099,7 @@ HorizontalAlignment RenderText::GetCurrentHorizontalAlignment() {
 
 Vector2d RenderText::GetAlignmentOffset(size_t line_number) {
   // TODO(ckocagil): Enable |lines_| usage on RenderTextMac.
-  if (multiline_)
+  if (MultilineSupported() && multiline_)
     DCHECK_LT(line_number, lines_.size());
   Vector2d offset;
   HorizontalAlignment horizontal_alignment = GetCurrentHorizontalAlignment();