Unit tests for misspelled policy names.

Unit tests for misspelled policy names.

This verifies that we detect and report misspelled policy names
regardless of whether "RemoteAccessHost" appears as a prefix,
suffix or a substring.  I felt adding this test is important
to "document" the behavior asked about in
https://codereview.chromium.org/966433002/diff/120001/remoting/host/policy_watcher.cc#newcode109

The new test verifies expected behavior via MockLog class moved to base/test in
crrev.com/966423003.  I feel that the benefit of documenting and automatically
verifying the expected behavior outweights the small maintenence cost of an
additional test and the slight ickyness of verifying the behavior by looking at
log output.

BUG=

Committed: https://crrev.com/bfe7577b0faa92b2fc912b7bbfe85bd994ac7e33
Cr-Commit-Position: refs/heads/master@{#319172}

[Łukasz Anforowicz, 2015-03-04 22:08:57]

Patchset #1 (id:1) has been deleted

[Łukasz Anforowicz, 2015-03-04 22:11:36]

lukasza@chromium.org changed reviewers:
+ rmsousa@chromium.org

[Łukasz Anforowicz, 2015-03-04 22:11:36]

Renato, could you please take a look?

[rmsousa, 2015-03-04 23:32:26]

lgtm

[Łukasz Anforowicz, 2015-03-04 23:54:24]

The CQ bit was checked by lukasza@chromium.org

[commit-bot: I haz the power, 2015-03-04 23:55:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/979823004/20001

[commit-bot: I haz the power, 2015-03-05 00:28:20]

Committed patchset #1 (id:20001)

[commit-bot: I haz the power, 2015-03-05 00:29:09]

Patchset 1 (id:??) landed as
https://crrev.com/bfe7577b0faa92b2fc912b7bbfe85bd994ac7e33
Cr-Commit-Position: refs/heads/master@{#319172}