Mac: Disable r470769. I.e., Don't pump chrome tasks in private message loop modes.

It interacts badly with NSMenus on the native print dialog.

To fix, we may need to use a scoping class that adds these modes only
for menus that Chrome runs. Defer that to m61.

BUG=726200, 602914, 640466
TEST=Click the "Print using system dialog..." link in Print Preview,
then select "Save as PDF" via the [PDF] button in the native print
dialog. Chrome shouldn't hang.

Review-Url: https://codereview.chromium.org/2898953006
Cr-Commit-Position: refs/heads/master@{#474621}
1 file changed