Fix the DCHECK failure in render_text_harfbuzz.cc.

ui/gfx/render_text_harfbuzz.cc

Index: ui/gfx/render_text_harfbuzz.cc
diff --git a/ui/gfx/render_text_harfbuzz.cc b/ui/gfx/render_text_harfbuzz.cc
index 39f00409700ab1cabd97b6a76e9bbd569bc78e9a..87ce7bab1965c7be32b8cf2498e8c8d7f6ccf8bb 100644
--- a/ui/gfx/render_text_harfbuzz.cc
+++ b/ui/gfx/render_text_harfbuzz.cc
@@ -404,9 +404,6 @@ class HarfBuzzLineBreaker {
       // Merge segments that belong to the same run.
       if (last_segment.run == segment.run) {
         DCHECK_EQ(last_segment.char_range.end(), segment.char_range.start());
-        DCHECK_LE(
-            std::abs(last_segment.x_range.end() - segment.x_range.start()),
-            std::numeric_limits<float>::epsilon());

[msw, 2016/05/04 22:03:59]

It seems like there's likely floating math rounding errors somewhere (failing on
3.05176e-05 vs. 1.19209e-07). I think it's still a useful DCHECK if we just
change it to check that the difference is less than 1.0f (ie. there's less than
a pixel between one run and the next)? They really should be equal, but checking
<1.0f is better than nothing at all. WDYT?

[xdai1, 2016/05/04 22:49:46]

I agree with you. Thanks for your suggestion!

         last_segment.char_range.set_end(segment.char_range.end());
         last_segment.x_range.set_end(SkScalarToFloat(text_x_) +
                                      segment.width());