Add RenderText DirectionalityMode enum and support; etc.

ui/gfx/render_text_mac.cc

Index: ui/gfx/render_text_mac.cc
diff --git a/ui/gfx/render_text_mac.cc b/ui/gfx/render_text_mac.cc
index fcf0cf89f99c5bac614a2f495aa5a6f0a720aa86..1b313f793ae8808aac9cb81b1f62294d26edaba2 100644
--- a/ui/gfx/render_text_mac.cc
+++ b/ui/gfx/render_text_mac.cc
@@ -87,10 +87,6 @@ RenderTextMac::RenderTextMac() : common_baseline_(0), runs_valid_(false) {
 RenderTextMac::~RenderTextMac() {
 }
 
-base::i18n::TextDirection RenderTextMac::GetTextDirection() {
-  return base::i18n::LEFT_TO_RIGHT;
-}
-
 Size RenderTextMac::GetStringSize() {
   EnsureLayout();
   return string_size_;
@@ -183,6 +179,9 @@ void RenderTextMac::EnsureLayout() {
   base::mac::ScopedCFTypeRef<CFMutableAttributedStringRef> attr_text_mutable(
       CFAttributedStringCreateMutableCopy(NULL, 0, attr_text));
 
+  // TODO(asvitkine|msw): Respect GetTextDirection(), which may not match the
+  // natural text direction. See kCTTypesetterOptionForcedEmbeddingLevel, etc.
+
   ApplyStyles(attr_text_mutable, ct_font);
   line_.reset(CTLineCreateWithAttributedString(attr_text_mutable));