GitLab

This CL includes some small refactors to JNI calls for a11y
Android code.

We eliminate some trips through the JNI with the following updates:

 - announceLiveRegion checks empty strings before JNI call
 - Combine 4 populate AccessibilityEvent JNI calls to 1
 - Combine 2 populate AccessibilityNodeInfo JNI calls to 1
 - Update setting AccessibilityNodeInfo child ids to pass a
   vector once, rather than calling through JNI for each child

AX-Relnotes: N/A
Change-Id: Ic6c46b8316ebc954a20084844f5f072149a218d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2569852Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Mark Schillaci <mschillaci@google.com>
Commit-Queue: Mark Schillaci <mschillaci@google.com>
Cr-Commit-Position: refs/heads/master@{#833454}