Prevent infinite loop about itemizing text in RenderTextHarfBuzz.

ui/gfx/render_text_unittest.cc

 // 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.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/i18n/break_iterator.h"
@@ skipping 2559 matching lines @@
   EXPECT_EQ(Range(0, 0), run.CharRangeToGlyphRange(Range(4, 5)));
   EXPECT_EQ(Range(0, 0),
             internal::RoundRangeF(run.GetGraphemeBounds(iter.get(), 4)));
   Range chars;
   Range glyphs;
   run.GetClusterAt(4, &chars, &glyphs);
   EXPECT_EQ(Range(3, 8), chars);
   EXPECT_EQ(Range(0, 0), glyphs);
 }
 
+// Ensures RenderTextHarfBuzz::ItemizeTextToRuns() does not enter into an
+// infinite loop. See crbug.com/403892.
+TEST_F(RenderTextTest, HarfBuzz_InfiniteLoop) {
+  RenderTextHarfBuzz render_text;
+  render_text.SetObscured(true);
+  render_text.SetText(UTF8ToUTF16("\xF0\x9F\x98\x81y"));
+  gfx::Canvas canvas;
+  render_text.Draw(&canvas);
+}
+
 // Ensure a string fits in a display rect with a width equal to the string's.
 TEST_F(RenderTextTest, StringFitsOwnWidth) {
   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
   const base::string16 kString = ASCIIToUTF16("www.example.com");
 
   render_text->SetText(kString);
   render_text->ApplyStyle(BOLD, true, Range(0, 3));
   render_text->SetElideBehavior(ELIDE_TAIL);
 
   render_text->SetDisplayRect(Rect(0, 0, 500, 100));
@@ skipping 232 matching lines @@
   string_size.set_width(string_size.width() / 2);
   render_text.SetDisplayRect(gfx::Rect(string_size));
   render_text.EnsureLayout();
   CFIndex glyph_count = CTLineGetGlyphCount(render_text.line_);
   EXPECT_GT(text.size(), static_cast<size_t>(glyph_count));
   EXPECT_NE(0, glyph_count);
 }
 #endif
 
 }  // namespace gfx