Fix two flaky media notification tests

Fix two flaky media notification tests

There are two media notification tests flaky because of the test
pages are not set properly in BUILD.gn. This CL adds two test
pages in `media/session` test data directory so that they are
copied onto the device as they are executed. The `media/session`
test data directory is already in BUILD.gn so no changes there
needed.

BUG=697453
Review-Url: https://codereview.chromium.org/2722233002
Cr-Commit-Position: refs/heads/master@{#453991}
(cherry picked from commit 778f0744fecc3c50d4d23b0df97e3eaef9cbf817)

Review-Url: https://codereview.chromium.org/2731153002 .
Cr-Commit-Position: refs/branch-heads/2987@{#764}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/739dd695c7e6b6481b97ecf6e0b5e8ee63a75f83

[Zhiqiang Zhang (Slow), 2017-03-04 13:27:04]

Description was changed from

==========
Fix two flaky media notification tests

There are two media notification tests flaky because of the test
pages are not set properly in BUILD.gn. This CL adds two test
pages in `media/session` test data directory so that they are
copied onto the device as they are executed. The `media/session`
test data directory is already in BUILD.gn so no changes there
needed.

BUG=697453

Review-Url: https://codereview.chromium.org/2722233002
Cr-Commit-Position: refs/heads/master@{#453991}
(cherry picked from commit 778f0744fecc3c50d4d23b0df97e3eaef9cbf817)
==========

to

==========
Fix two flaky media notification tests

There are two media notification tests flaky because of the test
pages are not set properly in BUILD.gn. This CL adds two test
pages in `media/session` test data directory so that they are
copied onto the device as they are executed. The `media/session`
test data directory is already in BUILD.gn so no changes there
needed.

BUG=697453

Review-Url: https://codereview.chromium.org/2722233002
Cr-Commit-Position: refs/heads/master@{#453991}
(cherry picked from commit 778f0744fecc3c50d4d23b0df97e3eaef9cbf817)

Review-Url: https://codereview.chromium.org/2731153002 .
Cr-Commit-Position: refs/branch-heads/2987@{#764}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/739dd695c7e6b6481b97ecf6e0b5...
==========

[Zhiqiang Zhang (Slow), 2017-03-04 13:27:05]

Committed patchset #1 (id:1) manually as
739dd695c7e6b6481b97ecf6e0b5e8ee63a75f83.