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While working on http://codereview.chromium.org/9875026/ , I ended up needing to put a content::Referrer into the prerender_messages.  The problem was that it's already used in view_messages, and the compile would fail due to duplicate definitions.  The CommonParamTraits approach here avoids this problem by explicitly including a serializer and deserializer.

BUG=None

Review URL: http://codereview.chromium.org/10134024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@133915 0039d316-1c4b-4281-b951-d872f2087c98