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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d8fd6f68373fbe065c9d51d64ab02eafef02701f

commit d8fd6f68373fbe065c9d51d64ab02eafef02701f
Author: Emil A Eklund <eae@chromium.org>
Date: Thu Jul 12 22:45:09 2018

Add support for shaping latin-1

Add support for shaping latin-1 without first up-converting to UTF-16 in
HarfBuzzShaper and to the LayoutNG text layout & line breaking pipeline.

This allow for moderate improvements in memory usage and performance for
latin-1 content, espeically for subsequent layouts as text up-convertion
is avoided therefore allowing script segmentation to be avoided as well.

Notably the layout/line-layout-repeat-append performance test gets twice
as fast with this change. Other layout perf tests improve very slightly.

Increases performance of the ShapingLineBreakerPerfTest::ShapeLatinText
micro benchmark by about 5x. From 200 runs/s to 1000 runs/s on a T430s.

Legacy layout retains the UTF-16 up-conversion logic and isn't affected.

Bug: 636993,  693704 
Test: perf_tests/layout/line-layout-repeat-append.html
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I7fdb9ab228b61b22e9ef39cdfb8de6c360e83e3f
Reviewed-on: https://chromium-review.googlesource.com/1132270
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574759}
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/core/layout/ng/inline/ng_inline_node.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/core/layout/ng/inline/ng_line_breaker.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/core/layout/ng/inline/ng_line_truncator.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/caching_word_shape_iterator.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/case_mapping_harf_buzz_buffer_filler.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/case_mapping_harf_buzz_buffer_filler.h
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/harf_buzz_shaper.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/harf_buzz_shaper.h
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/harf_buzz_shaper_fuzzer.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/harf_buzz_shaper_test.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/fonts/shaping/shaping_line_breaker_test.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/testing/shaping_line_breaker_perf_test.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/text/text_run.cc
[modify] https://crrev.com/d8fd6f68373fbe065c9d51d64ab02eafef02701f/third_party/blink/renderer/platform/text/text_run.h