The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/663b6e203bd2f8e041f32b1963f6a794877fde41

commit 663b6e203bd2f8e041f32b1963f6a794877fde41
Author: Dominic Mazzoni <dmazzoni@chromium.org>
Date: Fri Feb 16 23:55:39 2018

Android accessibility: Only expose character locations on some elements

On Android, we can expose EXTRA_DATA_TEXT_CHARACTER_LOCATION_KEY
on accessible nodes in order to allow services like Select To Speak
to get the bounding box of individual characters or character
ranges.

When we implemented support for this, we exposed it on almost any
element, but this leads to Select To Speak not being able to
distinguish between real text, and things like images with no
visible text that it might be able to OCR.

Fix this by exposing this character location key only on nodes
that are static text or have a static text descendant.

Add a test that covers some common cases.

BUG= 812772 

Change-Id: I48941edfaa7522fdd36a5bd7fc88a0a4054713f3
Reviewed-on: https://chromium-review.googlesource.com/922688
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537465}
[modify] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/browser/accessibility/accessibility_tree_formatter_android.cc
[modify] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/browser/accessibility/browser_accessibility_android.cc
[modify] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/browser/accessibility/browser_accessibility_android.h
[modify] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
[modify] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/browser/accessibility/web_contents_accessibility_android.cc
[add] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/test/data/accessibility/html/character-locations-expected-android.txt
[add] https://crrev.com/663b6e203bd2f8e041f32b1963f6a794877fde41/content/test/data/accessibility/html/character-locations.html