Add multiline support to RenderTextHarfBuzz.

ui/gfx/render_text_harfbuzz.h

Index: ui/gfx/render_text_harfbuzz.h
diff --git a/ui/gfx/render_text_harfbuzz.h b/ui/gfx/render_text_harfbuzz.h
index 7f3a1dcef7396fb5b5f84af79d7d12a7a63a3c15..d0e167ecbed1cc421ec7b9eef17fb1aa0d8e50f1 100644
--- a/ui/gfx/render_text_harfbuzz.h
+++ b/ui/gfx/render_text_harfbuzz.h
@@ -113,6 +113,7 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
 
  private:
   friend class RenderTextTest;
+  FRIEND_TEST_ALL_PREFIXES(RenderTextTest, Multiline_NormalWidth);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_RunDirection);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByUnicodeBlocks);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByEmoji);
@@ -121,6 +122,13 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_NonExistentFont);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_UniscribeFallback);
 
+  // Specify the width of a glyph for test. The width of glyphs is very
+  // platform-dependent and environment-dependent. Otherwise multiline test
+  // will become really flaky.
+  void set_glyph_width_for_test(uint8 test_width) {
+    glyph_width_for_test_ = test_width;
+  }
+
   // Return the run index that contains the argument; or the length of the
   // |runs_| vector if argument exceeds the text length or width.
   size_t GetRunContainingCaret(const SelectionModel& caret) const;
@@ -168,6 +176,12 @@ class GFX_EXPORT RenderTextHarfBuzz : public RenderText {
   // be NULL in case of an error.
   scoped_ptr<base::i18n::BreakIterator> grapheme_iterator_;
 
+  // The total size of the layouted text.
+  SizeF total_size_;
+
+  // Fixed width of glyphs. This should only be set in test environments.
+  uint8 glyph_width_for_test_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderTextHarfBuzz);
 };