Use base::StringPairs where appropriate from /content

Use base::StringPairs where appropriate from /content

Because base/strings/string_split.h defines:
typedef std::vector<std::pair<std::string, std::string> > StringPairs;

BUG=412250
Committed: https://crrev.com/542c416be33f1cc748530f20db2025f43f490b30
Cr-Commit-Position: refs/heads/master@{#296649}

[anujsharma, 2014-09-25 04:01:35]

anujk.sharma@samsung.com changed reviewers:
+ avi@chromium.org

[anujsharma, 2014-09-25 04:01:38]

PTAL

[Avi (use Gerrit), 2014-09-25 04:07:09]

lgtm

[anujsharma, 2014-09-25 04:07:28]

On 2014/09/25 04:07:09, Avi wrote:
> lgtm

Thanks Avi for lgtm

[anujsharma, 2014-09-25 04:07:33]

The CQ bit was checked by anujk.sharma@samsung.com

[commit-bot: I haz the power, 2014-09-25 04:08:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/600163003/1

[commit-bot: I haz the power, 2014-09-25 05:02:03]

Committed patchset #1 (id:1) as f97693bcf7cb1827da974756971db3c91666a1d6

[commit-bot: I haz the power, 2014-09-25 05:03:07]

Patchset 1 (id:??) landed as
https://crrev.com/542c416be33f1cc748530f20db2025f43f490b30
Cr-Commit-Position: refs/heads/master@{#296649}