Stop combining text runs which are connected by 'COMMON' blocks.

ui/gfx/text_utils.h

 // Copyright 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_UTILS_H_
 #define UI_GFX_TEXT_UTILS_H_
 
 #include "base/strings/string16.h"
 #include "ui/gfx/gfx_export.h"
 
@@ skipping 13 matching lines @@
 
 // Returns the number of horizontal pixels needed to display the specified
 // |text| with |font_list|.
 GFX_EXPORT int GetStringWidth(const base::string16& text,
                               const FontList& font_list);
 
 // This is same as GetStringWidth except that fractional width is returned.
 GFX_EXPORT float GetStringWidthF(const base::string16& text,
                                  const FontList& font_list);
 
+// Returns a valid cut boundary at or before |index|. The surrogate pair and
+// combined characters should not be separated.
+GFX_EXPORT size_t
+FindValidBoundaryBefore(const base::string16& text, size_t index);

[msw, 2015/06/03 00:32:04]

nit: Is this the correct line breaking according to the style guide? I thought
we only put the export and return type on a separate line if they didn't fit on
the same line as the function name without args. I suspect this should be
something like this (and ditto below):
GFX_EXPORT size_t FindValidBoundaryBefore(const base::string16& text,
                                          size_t index);

[xdai1, 2015/06/06 00:05:19]

Yes, this is the correct line breaking. It's generated by running "git cl
format". I agree it's weird...

+
+// Returns a valid cut boundary at or after |index|. The surrogate pair and
+// combined characters should not be separated.
+GFX_EXPORT size_t
+FindValidBoundaryAfter(const base::string16& text, size_t index);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_TEXT_UTILS_H_