GitLab

AXEventGenerator::Iterator iterates over the generated events in
std::map<AXNode*, std::set<EventParams>> tree_events_. Often there
could be entry with empty event sets (std::set<EventParams) in
|tree_events_|, and if these empty event sets happen to be the first
entry when we iterate over |tree_events_|, AXEventGenerator::Iterator
::operator++ would increment AXEventGenerator::Iterator::set_iter_
past its end, causing an exception.

This CL fixes this issue by making AXEventGenerator::Iterator
::begin() to always point to a non-empty std::set<EventParams> entry
in |tree_events_|.

AX-Relnotes: n/a

Bug: 1120281
Change-Id: I8fbdbbc92eb007d3ce01bfa5cb61730c9f38c115
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2399560
Commit-Queue: Victor Fei <vicfei@microsoft.com>
Reviewed-by: Ian Prest <iapres@microsoft.com>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810485}