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

ui/gfx/render_text_harfbuzz.h

 // Copyright 2014 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_RENDER_TEXT_HARFBUZZ_H_
 #define UI_GFX_RENDER_TEXT_HARFBUZZ_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "third_party/harfbuzz-ng/src/hb.h"
@@ skipping 97 matching lines @@
   // Initialize the index mapping.
   void InitIndexMap();
 
   // Precomputes the offsets for all runs.
   void ComputePrecedingRunWidths();
 
   // Get the total width of runs, as if they were shown on one line.
   // Do not use this when multiline is enabled.
   float width() const { return width_; }
 
+  // Get the run index applicable to |position| (at or preceeding |position|).
+  size_t GetRunIndexAt(size_t position) const;
+
  private:
   // Text runs in logical order.
   ScopedVector<TextRunHarfBuzz> runs_;
 
   // Maps visual run indices to logical run indices and vice versa.
   std::vector<int32_t> visual_to_logical_;
   std::vector<int32_t> logical_to_visual_;
 
   float width_;
 
@@ skipping 30 matching lines @@
   size_t TextIndexToDisplayIndex(size_t index) override;
   size_t DisplayIndexToTextIndex(size_t index) override;
   bool IsValidCursorIndex(size_t index) override;
   void OnLayoutTextAttributeChanged(bool text_changed) override;
   void OnDisplayTextAttributeChanged() override;
   void EnsureLayout() override;
   void DrawVisualText(Canvas* canvas) override;
 
  private:
   friend class RenderTextTest;
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, Multiline_LineBreakerBehavior);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, Multiline_HorizontalAlignment);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, Multiline_NormalWidth);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, Multiline_WordWrapBehavior);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_RunDirection);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_HorizontalPositions);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest,
                            HarfBuzz_TextPositionWithFractionalSize);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByUnicodeBlocks);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByEmoji);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_SubglyphGraphemeCases);
@@ skipping 85 matching lines @@
 
   // Fixed width of glyphs. This should only be set in test environments.
   float glyph_width_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderTextHarfBuzz);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_HARFBUZZ_H_