Revert of Upstream string_util function.

Revert of Upstream string_util function. (patchset #4 id:60001 of https://codereview.chromium.org/1073863005/)

Reason for revert:
Causes checkdeps failures:
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests/builds/23234/steps/checkdeps/logs/stdio

ERROR in /mnt/data/b/build/slave/Linux_Tests/build/src/ios/chrome/test/ios_chrome_unit_test_suite.cc
  Illegal include: "ios/public/test/test_chrome_browser_provider.h"
    Because of "-ios" from ios's include_rules.
  Illegal include: "ios/public/test/test_chrome_provider_initializer.h"
    Because of "-ios" from ios's include_rules.
  Illegal include: "ios/web/public/web_client.h"
    Because of "-ios" from ios's include_rules.
  Illegal include: "ui/base/ui_base_paths.h"
    Because of no rule applying.

ERROR in /mnt/data/b/build/slave/Linux_Tests/build/src/ios/chrome/test/testing_application_context.cc
  Illegal include: "ios/public/provider/chrome/browser/chrome_browser_provider.h"
    Because of "-ios" from ios's include_rules.

FAILED

Original issue's description:
> Upstream string_util function.
>
> Create ios/chrome/common as these functions may be needed by external components.
>
> Narrowing DEPS from ios/chrome to ios/chrome/browser.
>
> TBR=mef, sdefresne,rsesek, thakis
>
> Committed: https://crrev.com/09508e0b6219f0febf9a609e1c9ff6d6eb6dde8e
> Cr-Commit-Position: refs/heads/master@{#324860}

TBR=sdefresne@chromium.org,droger@chromium.org,thakis@chromium.org,rsesek@chromium.org,mef@chromium.org,olivierrobin@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/525b51d20d0249a559ab791d01e464ba3e43dae6
Cr-Commit-Position: refs/heads/master@{#324877}

[Mark P, 2015-04-13 17:39:10]

Created Revert of Upstream string_util function.

[commit-bot: I haz the power, 2015-04-13 17:40:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1066013003/1

[commit-bot: I haz the power, 2015-04-13 17:43:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-13 17:44:48]

Patchset 1 (id:??) landed as
https://crrev.com/525b51d20d0249a559ab791d01e464ba3e43dae6
Cr-Commit-Position: refs/heads/master@{#324877}