Revert of Add policy_templates target for GN.

Revert of Add policy_templates target for GN. (patchset #4 id:60001 of https://codereview.chromium.org/957283003/)

Reason for revert:
Possibly broke some GN builds (reverted with https://codereview.chromium.org/865573002), e.g.:

http://build.chromium.org/p/chromium.linux/builders/Linux%20GN/builds/24483/steps/compile/logs/stdio
http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20GN/builds/11092/steps/compile/logs/stdio

ninja: Entering directory `/mnt/data/b/build/slave/Linux_GN/build/src/out/Release'
ninja:error: expected depfile 'gen/chrome/policy_templates.d' to mention 'gen/chrome/app/policy/common/html/am/chrome_policy_list.html', got 'gen/chrome/app/policy/linux/examples/chrome.json'

Original issue's description:
> Add policy_templates target for GN.
>
> BUG=462362
>
> Committed: https://crrev.com/982eb90bf74535cbe5e21c4eacb759c42ff424d4
> Cr-Commit-Position: refs/heads/master@{#319759}

TBR=pneubeck@chromium.org,bauerb@chromium.org,knn@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=462362
Committed: https://crrev.com/a164bcfcacb9fdf84bf73a0b98042424aada3b55
Cr-Commit-Position: refs/heads/master@{#319774}

[dgrogan, 2015-03-09 23:46:47]

Created Revert of Add policy_templates target for GN.

[commit-bot: I haz the power, 2015-03-09 23:48:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/992863002/1

[commit-bot: I haz the power, 2015-03-09 23:49:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-09 23:49:58]

Patchset 1 (id:??) landed as
https://crrev.com/a164bcfcacb9fdf84bf73a0b98042424aada3b55
Cr-Commit-Position: refs/heads/master@{#319774}

[knn, 2015-03-10 11:34:15]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/996653002/ by knn@chromium.org.

The reason for reverting is: This did not break the build..