[Extensions] Adjust strings in the extension message bubble

[Extensions] Adjust strings in the extension message bubble

Adjust the strings in the extension message bubble to indicate which extension
is overriding certain settings if it's not point to a specific one. If it is
pointing to a specific one, use "This extension".

BUG=485614
Committed: https://crrev.com/5b9b392da0f2fb995f14bea06c11f87a3c33510a
Cr-Commit-Position: refs/heads/master@{#329873}

[Devlin, 2015-05-08 17:13:17]

rdevlin.cronin@chromium.org changed reviewers:
+ asargent@chromium.org

[Devlin, 2015-05-08 17:13:17]

Antony, mind taking a look?  This fixes the strings in crbug.com/485614; the
anchoring is being fixed in a different CL.

[asargent_no_longer_on_chrome, 2015-05-08 19:15:12]

lgtm

[Devlin, 2015-05-08 22:00:04]

The CQ bit was checked by rdevlin.cronin@chromium.org

[commit-bot: I haz the power, 2015-05-08 22:04:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1125403006/1

[commit-bot: I haz the power, 2015-05-09 00:57:14]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-09 00:57:15]

Try jobs failed on following builders:
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_TIMED_OUT,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[Devlin, 2015-05-14 17:00:22]

The CQ bit was checked by rdevlin.cronin@chromium.org

[Devlin, 2015-05-14 17:00:23]

The patchset sent to the CQ was uploaded after l-g-t-m from
asargent@chromium.org
Link to the patchset: https://codereview.chromium.org/1125403006/#ps20001
(title: "Latest master")

[commit-bot: I haz the power, 2015-05-14 17:00:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1125403006/20001

[commit-bot: I haz the power, 2015-05-14 17:53:15]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-14 17:54:56]

Patchset 2 (id:??) landed as
https://crrev.com/5b9b392da0f2fb995f14bea06c11f87a3c33510a
Cr-Commit-Position: refs/heads/master@{#329873}