Replace StyleRange with BreakList; update RenderText, etc.

ui/gfx/text_constants.h

Index: ui/gfx/text_constants.h
diff --git a/ui/gfx/text_constants.h b/ui/gfx/text_constants.h
index 3c644ab77e83cfbfbc54fa3d38143767aa04bac3..4ac788e6109ec61ab09826065b5415bad1d455cf 100644
--- a/ui/gfx/text_constants.h
+++ b/ui/gfx/text_constants.h
@@ -40,6 +40,17 @@ enum DirectionalityMode {
   DIRECTIONALITY_FORCE_RTL,
 };
 
+// Text styles and adornments.
+// TODO(msw): Merge with gfx::Font::FontStyle.
+enum TextStyle {

[Alexei Svitkine (slow), 2013/01/23 16:52:54]

Have you considered making these values powers of 2?

Then, for places that need to keep track of a set of styles, a flags field can
be used. (Obviously, similar to the Font constants).

This would make it so you don't need to keep a set of bools around to track
these when dealing with e.g. runs in RenderText impls.

(Of course when the param is a TextStyle, it should only be one flag, whereas an
int should be used for a set of flags, which we can document here for clarity.)

[msw, 2013/01/25 09:10:02]

As we discussed offline, this would be nice, but makes indexing by style
difficult/costly; I'm open to further suggestions.

+  BOLD = 0,
+  ITALIC,
+  STRIKE,
+  DIAGONAL_STRIKE,
+  UNDERLINE,
+  NUM_TEXT_STYLES,
+};
+
 }  // namespace gfx
 
 #endif  // UI_GFX_TEXT_CONSTANTS_H_