Clean up ProfileManager interface.

Clean up ProfileManager interface:

1) Don't require passing in the user data directory everywhere. ProfileManager already knows the user data directory, and any place that might want to change it will override the value in the PathService.
2) Remove static helper methods that just forward to the corresponding instance method. In part this is necessary to avoid clashes with instance methods that now don't take a parameter anymore, and it also removes ambiguity about how to call these methods. In many cases, callers already had a ProfileManager anyway, and in addition, in some cases the static method was then called via the instance.

BUG=none

[Bernhard Bauer, 2015-05-19 20:39:30]

The CQ bit was checked by bauerb@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-05-19 20:40:21]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1128173005/160001

[commit-bot: I haz the power, 2015-05-19 20:46:01]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-19 20:46:02]

Dry run: Try jobs failed on following builders:
  mac_chromium_compile_dbg_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[Bernhard Bauer, 2015-05-27 21:56:17]

The CQ bit was checked by bauerb@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-05-27 21:58:09]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1128173005/200001

[commit-bot: I haz the power, 2015-05-27 22:04:21]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-27 22:04:22]

Dry run: Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)