Refactored ChromeViewHostMsg_SearchBoxNavigate IPC message related code.

      (1) InstantPage no longer process ChromeViewHostMsg_SearchBoxNavigate IPC message.
(2) SearchIPCRouter now handles ChromeViewHostMsg_SearchBoxNavigate IPC message.
(3) Removed unused params from SearchBox::NavigateToURL() and updated the message handler accordingly.
(4) Deprecated Instant navigation histogram since the HTML popup went away.

BUG=272583
TEST=none

Review URL: https://codereview.chromium.org/26643002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231413 0039d316-1c4b-4281-b951-d872f2087c98