GTK: add CHROME_NAMED_URL as a data type for drags from the omnibox.
GTK: add CHROME_NAMED_URL as a data type for drags from the omnibox.

This is required when we drag the url from omnibox to render widget of a tab, the tab should navigate to the dropped url.
 
BUG=53352
TEST=As described in the bug.

Review URL: http://codereview.chromium.org/8311014

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@107171 0039d316-1c4b-4281-b951-d872f2087c98

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