Send ChromeViewMsg_SearchBoxMarginChange IPC message from SearchIPCRouter.

BUG=272583
TEST=none

Review URL: https://codereview.chromium.org/130823004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248033 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248033