Move RemoveChars, ReplaceChars, TrimString, and TruncateUTF8ToByteSize to base namespace.

BUG=
R=viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/102843002

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@238465 4ff67af0-8c30-449e-8e8b-ad334ec8d88c