Move StringPrintf into its own file and use the base namespace. Currently this has using
directives for the functions so I don't have to change all files to use the namespace.

No code changes to logic.

TEST=it compiles + the included unit tests
BUG=none
Review URL: http://codereview.chromium.org/3181016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@56299 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/base.gyp b/base/base.gyp
index f401bf3..195e73a 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -135,6 +135,7 @@
         'string_split_unittest.cc',
         'string_tokenizer_unittest.cc',
         'string_util_unittest.cc',
+        'stringprintf_unittest.cc',
         'sys_info_unittest.cc',
         'sys_string_conversions_mac_unittest.mm',
         'sys_string_conversions_unittest.cc',