Make the ShortcutHelper toast instead of send the user home for web app banners
* Fix null pointer access when a shortcut is added via
a manifest. It was relying on the WebContents() being
accessible immediately after stopping the observation of
the WebContents.
* When adding a shortcut on the homescreen through web app
banners, stop firing Intents to send the user to the
home. Instead show a toast to indicate that a shortcut is
being added to their homescreen. The string was chosen by UI
and is described on the bug.
* Hopefully fix the ShortcutHelperTests.
BUG=457424,303486
TEST=ShortcutHelperTest
Review URL: https://codereview.chromium.org/934183002
Cr-Commit-Position: refs/heads/master@{#317079}
6 files changed
