CreateSharedMemory is allowed to return nullptr if memory can't be
allocated but DesktopFrameWin didn't check to ensure was allocated
before accessing it. This CL just adds a null check, logs a
warning, and returns nullptr which is already done lower in the
function and the error is correctly handled in the screen and window
capturers which call DesktopFrameWin::Create().
Bug: chromium:1251651
Change-Id: Ie9231f03ba9c7a96823af986b9df38f97fcb682c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/232663
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#35072}
0529791ef7