GitLab

Original CL: http://crrev.com/c/2275981
Revert: http://crrev.com/c/2284446

Reason for revert:
Builder: Linux ChromiumOS MSan Tests
https://ci.chromium.org/p/chromium/builders/ci/Linux%20ChromiumOS%20MSan%20Tests/b8875468439609281712

The failures were caused as |push_button.is_read_only| was not
initialized in TestButtonNodeCreation before usage. This CL fixes this
issue.

Original description:
This CL creates button nodes using PdfAccessibilityButtonInfo sent from
plugin process and inserts them in the PdfAccessibilityTree.

This CL also includes test to validate the creation of button nodes in
PdfAccessibilityTree.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_chromium_chromeos_msan_rel_ng

Bug: 1030242
Change-Id: Id821ea02f92c20b5f5eb3190e4d878c6bd52edea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2284505Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Ankit Kumar 🌪️ <ankk@microsoft.com>
Commit-Queue: Mansi Awasthi <maawas@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#786155}