[Merge] Cancel uninstall if the uninstall dialog's parent window is destroyed prior to the uninstall dialog showing.

BUG=424999, 397396
TEST=ExtensionUninstallDialogViewBrowserTest.TrackParentWindowDestruction
TBR=pkotwicz

Review URL: https://codereview.chromium.org/697023002

Review URL: https://codereview.chromium.org/711343003

Cr-Commit-Position: refs/branch-heads/2171@{#402}
Cr-Branched-From: 267aeeb8d85c8503a7fd12bd14654b8ea78d3974-refs/heads/master@{#297060}
6 files changed