CPP: Make r570 compile in Chromium.

CPP: Make r570 compile in Chromium.

This CL ensures that:
- All declarations in headers are made in the i18n::phonenumbers namespace.
- All USE flags/macros are prefixed with I18N_PHONENUMBERS_ to avoid name
  clashes.
- All the code in base/ is actually used (by deleting unused code).
- Outdated occurrences of USE_GOOGLE_BASE don't exist anymore.
- Logging in PhoneNumberUtil is disabled by default (in production). However it
  can be enabled by calling PhoneNumberUtil::SetLogger() as it is now done
  during testing.

BUG=http://crbug.com/236272
R=jia.shao.peng@gmail.com

Review URL: https://codereview.appspot.com/9162043

git-svn-id: http://libphonenumber.googlecode.com/svn/trunk@571 ee073f10-1060-11df-b6a4-87a95322a99c