The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cb1e0169211135db1dd2e0220434bcec2efd7f16

commit cb1e0169211135db1dd2e0220434bcec2efd7f16
Author: timvolodine <timvolodine@chromium.org>
Date: Mon Nov 28 20:28:32 2016

Spellcheck : Fix caching in cases where text is deleted.

This patch fixes spellcheck caching in the following case:
1. paragraph is edited by removing text from the back and
2. paragraph does not contain misspelled words.

Currently this case results in a cache miss and consequently
spellcheck requests being sent to the spellchecking service
while completely unnecessary. This fix applies to all
platforms.

This patch also adds a few unit tests for the relevant
caching specific behavior.

BUG= 664247 ,629609

Review-Url: https://codereview.chromium.org/2494123002
Cr-Commit-Position: refs/heads/master@{#434710}

[modify] https://crrev.com/cb1e0169211135db1dd2e0220434bcec2efd7f16/components/spellcheck/renderer/BUILD.gn
[modify] https://crrev.com/cb1e0169211135db1dd2e0220434bcec2efd7f16/components/spellcheck/renderer/spellcheck_provider.cc
[modify] https://crrev.com/cb1e0169211135db1dd2e0220434bcec2efd7f16/components/spellcheck/renderer/spellcheck_provider_test.cc
[modify] https://crrev.com/cb1e0169211135db1dd2e0220434bcec2efd7f16/components/spellcheck/renderer/spellcheck_provider_test.h
[add] https://crrev.com/cb1e0169211135db1dd2e0220434bcec2efd7f16/components/spellcheck/renderer/spellcheck_provider_unittest.cc

Your change meets the bar and is auto-approved for M56 (branch: 2924)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0529dbf676ae32842dfe480eb421dcb3ba9b7291

commit 0529dbf676ae32842dfe480eb421dcb3ba9b7291
Author: timvolodine <timvolodine@chromium.org>
Date: Fri Dec 02 16:09:00 2016

Spellcheck : Fix caching in cases where text is deleted.

Merge to M56 (branch 2924)

This patch fixes spellcheck caching in the following case:
1. paragraph is edited by removing text from the back and
2. paragraph does not contain misspelled words.

Currently this case results in a cache miss and consequently
spellcheck requests being sent to the spellchecking service
while completely unnecessary. This fix applies to all
platforms.

This patch also adds a few unit tests for the relevant
caching specific behavior.

BUG= 664247 ,629609
TBR=tobiasjs@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2494123002
Cr-Commit-Position: refs/heads/master@{#434710}
(cherry picked from commit cb1e0169211135db1dd2e0220434bcec2efd7f16)

Review-Url: https://codereview.chromium.org/2548823002
Cr-Commit-Position: refs/branch-heads/2924@{#287}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}

[modify] https://crrev.com/0529dbf676ae32842dfe480eb421dcb3ba9b7291/components/spellcheck/renderer/BUILD.gn
[modify] https://crrev.com/0529dbf676ae32842dfe480eb421dcb3ba9b7291/components/spellcheck/renderer/spellcheck_provider.cc
[modify] https://crrev.com/0529dbf676ae32842dfe480eb421dcb3ba9b7291/components/spellcheck/renderer/spellcheck_provider_test.cc
[modify] https://crrev.com/0529dbf676ae32842dfe480eb421dcb3ba9b7291/components/spellcheck/renderer/spellcheck_provider_test.h
[add] https://crrev.com/0529dbf676ae32842dfe480eb421dcb3ba9b7291/components/spellcheck/renderer/spellcheck_provider_unittest.cc

timvolodine@ Could you please provide the sample html file or TEST steps and expected behavior if this can be verified manually.

Thanks,

This is a performance optimization with blink-level tests in the patch. Unless you measure performance/battery/response times not really for manual testing ;)