Non-US OS region generates invalid trace JSON.

JSON output from the trace logging has floats formatted
to the current user locale, which can make opening the
trace fail.

R=
BUG=304818

Review URL: https://codereview.chromium.org/26249002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227730 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227730
Add unit test for google_apis::RequestSender.

BUG=161207, 251104

Review URL: https://codereview.chromium.org/26617003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227731 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227731