Make base::RefCountedBase methods inline

Make base::RefCountedBase methods inline as it gives a performance impact (especially considering plenty of ref-counted objects and a lack of optimization for passing scoped_refptrs into functions -- there is no analogue to WTF::PassRefPtr).

Review URL: https://codereview.chromium.org/88993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238956 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238956