The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9998d3836603c74d05443573f1e5550e88b9111d

commit 9998d3836603c74d05443573f1e5550e88b9111d
Author: Katie D <katie@chromium.org>
Date: Wed Feb 21 01:00:31 2018

Make Clipboard API available to Closure for extensions to use.

This allows the Select-to-Speak extension to include the Clipboard
API as a dependency in compiled_resources2.gyp in a follow-up
change, for example https://chromium-review.googlesource.com/c/chromium/src/+/922444/.

Bug:  812683 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I0773415d7cc47e870ff4161e73b97df24819e78d
Reviewed-on: https://chromium-review.googlesource.com/922388
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537963}
[modify] https://crrev.com/9998d3836603c74d05443573f1e5550e88b9111d/extensions/common/api/clipboard.idl
[add] https://crrev.com/9998d3836603c74d05443573f1e5550e88b9111d/third_party/closure_compiler/externs/clipboard.js
[modify] https://crrev.com/9998d3836603c74d05443573f1e5550e88b9111d/third_party/closure_compiler/externs/compiled_resources2.gyp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e014c5d9087f8d8a88c5f5d3a442d591219244f3

commit e014c5d9087f8d8a88c5f5d3a442d591219244f3
Author: Katie D <katie@chromium.org>
Date: Wed Feb 21 21:32:31 2018

Use clipboard instead of selection on Google Drive apps.

When no nodes are found to be selected and in a Google Drive
app like sheets, slides, docs or drawings, read the contents
of the clipboard rather than speaking nothing.

See go/sts-selection-in-drive for more information.

Bug:  812683 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Id99482579dbfeeeebf2f3976d7ec4b24d11a9403
Reviewed-on: https://chromium-review.googlesource.com/922444
Commit-Queue: Katie Dektar <katie@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538212}
[modify] https://crrev.com/e014c5d9087f8d8a88c5f5d3a442d591219244f3/chrome/browser/resources/chromeos/select_to_speak/compiled_resources2.gyp
[modify] https://crrev.com/e014c5d9087f8d8a88c5f5d3a442d591219244f3/chrome/browser/resources/chromeos/select_to_speak/manifest.json.jinja2
[modify] https://crrev.com/e014c5d9087f8d8a88c5f5d3a442d591219244f3/chrome/browser/resources/chromeos/select_to_speak/select_to_speak.js
[modify] https://crrev.com/e014c5d9087f8d8a88c5f5d3a442d591219244f3/chrome/browser/resources/chromeos/select_to_speak/select_to_speak_unittest.gtestjs

Problems with focus found, reverting to Assigned to katie@ 

Google Chrome 67.0.3369.0 (Official Build) canary (64-bit)
Firmware Version Google_Samus.6300.276.0
Flag enabled: #enable-experimental-accessibility-features

# Launch any Google Doc - pass
# Invoke STS using search + s or highlighting feature
Text is read smoothly and highlight rendered correctly even across a table. 
Clipboard contents is indeed destroyed. 

# Launch any Google Sheet - fail
# Invoke STS using search + s or highlighting feature
Text is read but highlight remains on the entire Sheet instead of highlighting individual cells.
Clipboard contents is indeed destroyed.

# Launch any Google Slide - fail
# Invoke STS using search + s or highlighting feature
Invoking using search + drag works as expected. 
Invoking using highlight then Search + S the ext is read but highlight remains on the entire Slide instead of highlighting individual words.
Clipboard contents is indeed destroyed.

# Launch any Google Slide - fail
# Invoke STS using search + s or highlighting feature
Invoking using search + drag works as expected. 
Invoking using highlight then Search + S the text is read but highlight remains on the entire Slide instead of highlighting individual words.
Clipboard contents is indeed destroyed.

# Launch any Google Form (editing side) - unsure if pass or fail due to clipboard not being destroyed 
# Invoke STS using search + s or highlighting feature
Text is read smoothly and highlight rendered correctly even across a multiple sections of the page. 
Clipboard contents is NOT destroyed. 
Another bug is opened for this page here regarding comboboxes: 822554

 
# Launch any Google Form (preview/submission side) - pass
# Invoke STS using search + s or highlighting feature
Text is read smoothly and highlight rendered correctly even across multiple sections of the page. 
Clipboard contents is NOT destroyed. 
Another bug is opened for this page here regarding radio buttons: 822556


# Launch any Google Drawing with a text element - fail
# Invoke STS using search + s or highlighting feature
Invoking using search + drag works as expected. 
Invoking using highlight then Search + S the ext is read but highlight remains on the entire Drawing instead of highlighting individual words.
Clipboard contents is indeed destroyed.
 
# Launch any Google My Map - pass
# Invoke STS using search + s or highlighting feature
Text is read smoothly and highlight rendered correctly even across a table. 
Clipboard contents is NOT destroyed. 

# Launch any Google Site (editing side) - pass
# Invoke STS using search + s or highlighting feature
Text is read smoothly and highlight rendered correctly even across multiple sections of the page. 
Clipboard contents is NOT destroyed. 
Another bug is opened for this page here regarding reading buttons that aren't visible: 822557

Please let me know if I should open another bug for the discrepancy with focus between the two different ways to invoke STS or anything else.

This is working "correctly" for what's currently possible. See go/sts-selection-in-drive if you want more info.

* STS destroys the clipboard in Google Docs, Drawings, Slides and Sheets when using Search + S. This is expected.
* Word highlighting doesn't work in Google Docs, Drawings, Slides and Sheets when using Search + S. This is expected.
* The clipboard is not destroyed in Google Forms or Sites, this is correct. Clipboard is only destroyed in Docs, Drawings, Slides and Sheets.

We will need to update help center articles to make sure users understand these things.

Flipping to verified upon review of comments above by katie@. 

Moving from just having STS label to also having the UI>Accessibility>SelectToSpeak component to make searching easier in the future.