Replace StyleRange with BreakList; update RenderText, etc.

ui/gfx/text_constants.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_TEXT_CONSTANTS_H_
 #define UI_GFX_TEXT_CONSTANTS_H_
 
 namespace gfx {
 
 // TODO(msw): Distinguish between logical character stops and glyph stops?
@@ skipping 22 matching lines @@
   // Use the first strong character's direction.
   DIRECTIONALITY_FROM_TEXT = 0,
   // Use the UI locale's text reading direction.
   DIRECTIONALITY_FROM_UI,
   // Use LTR regardless of content or UI locale.
   DIRECTIONALITY_FORCE_LTR,
   // Use RTL regardless of content or UI locale.
   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_