Use base::StringPairs where appropriate from /chrome

Use base::StringPairs where appropriate from /chrome

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

BUG=412250
Committed: https://crrev.com/511524f1f79549928c5c223337abe09c9448ee49
Cr-Commit-Position: refs/heads/master@{#294707}

[limasdf, 2014-09-12 22:51:27]

limasdf@gmail.com changed reviewers:
+ thestig@chromium.org

[limasdf, 2014-09-12 22:51:28]

PTAL

[Lei Zhang, 2014-09-12 22:53:35]

The CQ bit was checked by thestig@chromium.org

[Lei Zhang, 2014-09-12 22:53:36]

lgtm

Thanks!

[commit-bot: I haz the power, 2014-09-12 22:59:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/568173004/1

[commit-bot: I haz the power, 2014-09-13 00:50:24]

Committed patchset #1 (id:1) as c58cd66adaef9f76f2e6bed4bb82ae6a0e4e4bd6

[commit-bot: I haz the power, 2014-09-13 00:54:44]

Patchset 1 (id:??) landed as
https://crrev.com/511524f1f79549928c5c223337abe09c9448ee49
Cr-Commit-Position: refs/heads/master@{#294707}