[TTS] Gather surrounding text on Tap before any UX.
Extract the text tapped on to use as a signal in Tap Suppression.
The text is extracted before any UX is displayed in order to allow the
tap to be totally ignored when appropriate. Feeding the surrounding
text into the logic of TTS will be done separately.
This adds several files that are part of the 2016-refactoring.
See crbug.com/624609 and go/cs-refactoring-2016.
This CL is part of the refactoring-2016 effort, see go/cs-refactoring-2016
for details.
BUG=634136, 624609
Review-Url: https://codereview.chromium.org/2211353002
Cr-Commit-Position: refs/heads/master@{#418464}
14 files changed
