Issue 606249  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b47c12e89f5134efe6a68cb45e28a92451fcdb3e

commit b47c12e89f5134efe6a68cb45e28a92451fcdb3e
Author: eae <eae@chromium.org>
Date: Tue Mar 28 00:41:24 2017

Add support for shaper-driven line breaking to HarfBuzzShaper

Shapes a line of text by finding the ideal break point based on existing
shape results for the paragraph and then looking backwards until a valid
and appropriate break opportunity is identified. Re-shapes the beginning
and/or end of the line as needed (if the break position affect shaping).

This allows for significantly faster and more efficient line breaking by
only re-shaping when absolutely needed and by only measuring between the
start/end of lines and the nearest suitable and valid break opportunity.

The nextSafeToBreakBefore and previousSafeToBreakAfter functions will be
updated to use safe-to-break information when exposed by HarfBuzz.

R=drott@chromium.org, kojii@chromium.org
BUG= 609117 
TEST=Source/platform/fonts/shaping/HarfBuzzShaperTest.cpp

Review-Url: https://codereview.chromium.org/2740083002
Cr-Commit-Position: refs/heads/master@{#459953}

[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.cpp
[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.h
[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaperTest.cpp
[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.cpp
[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/ShapeResult.h
[modify] https://crrev.com/b47c12e89f5134efe6a68cb45e28a92451fcdb3e/third_party/WebKit/Source/platform/fonts/shaping/ShapeResultInlineHeaders.h