Revert of Media Router GYP/GN cleanup

Revert of Media Router GYP/GN cleanup (patchset #14 id:260001 of https://codereview.chromium.org/1136623003/)

Reason for revert:
Broke Linux bots on Chromium waterfall, see

http://build.chromium.org/p/chromium/builders/Linux/builds/62091
http://build.chromium.org/p/chromium/buildstatus?builder=Linux%20x64&number=3231

The error in gclient runhooks is:

gyp: Key 'dependencies' repeated at level 3 with key path 'targets.3' while reading /b/build/slave/Linux_x64/build/src/chrome/browser/media/router/media_router.gyp

Not sure why this didn't show up on other bots or trybots.

Original issue's description:
> Media Router GYP/GN cleanup:
>
> - Refactor GYP and GN files to share source lists.
> - Extract a proper test_support target.
> - Fix upstream files with new target structure.
>
> BUG=461815, 464199, 464205
>
> Committed: https://crrev.com/9c5e5781517823c18144b0bb5b66b66a1afd6733
> Cr-Commit-Position: refs/heads/master@{#330002}

TBR=brettw@chromium.org,kmarshall@chromium.org,mfoltz@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=461815, 464199, 464205
Committed: https://crrev.com/680e2cbe12d71bafb3dc8128f651dbdd6fd84f5a
Cr-Commit-Position: refs/heads/master@{#330009}

[jam, 2015-05-15 01:17:57]

Created Revert of Media Router GYP/GN cleanup

[commit-bot: I haz the power, 2015-05-15 01:21:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1140183002/1

[commit-bot: I haz the power, 2015-05-15 01:24:33]

Committed patchset #1 (id:1)

[mark a. foltz, 2015-05-15 01:25:20]

lgtm

[commit-bot: I haz the power, 2015-05-15 01:26:07]

Patchset 1 (id:??) landed as
https://crrev.com/680e2cbe12d71bafb3dc8128f651dbdd6fd84f5a
Cr-Commit-Position: refs/heads/master@{#330009}