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- This CL updates the Permission Bubble Manager to autorespond for browser tests.
  The test tells the Permission Bubble Manager which response is desired, and the
  Permission Bubble Manager will execute that response immediately after Show().

- This CL applies the new responder to parameterized PushMessagingBrowsertests.

BUG=438758

Review URL: https://codereview.chromium.org/1154943008

Cr-Commit-Position: refs/heads/master@{#333166}