[Android Webapps] Remove context function parameters from WebappLauncherActivity

This CL removes the application context parameter from several functions in
WebappLauncherActivity and WebappAuthenticator.

BUG=None

Change-Id: Ie4486cb4f9950a34e6b8349806cab35ebbb8f5a0
Reviewed-on: https://chromium-review.googlesource.com/c/1354128
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612742}
6 files changed