Fix crash in TabContentsViewViews::Focus. This was caused by r125126. The subtle bug is that the SadTabHelper's Observe function use to reset TabContentsViewView's Widget pointer before it deleted the sad tab Widget. With my change, TabContentsViewWin would call SadTabHelper in the middle of its sad_tab_.reset() call and would use a Widget that's being destructed.
Fix crash in TabContentsViewViews::Focus. This was caused by r125126. The subtle bug is that the SadTabHelper's Observe function use to reset TabContentsViewView's Widget pointer before it deleted the sad tab Widget. With my change, TabContentsViewWin would call SadTabHelper in the middle of its sad_tab_.reset() call and would use a Widget that's being destructed.

BUG=117668
Review URL: https://chromiumcodereview.appspot.com/9733023

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@127686 0039d316-1c4b-4281-b951-d872f2087c98

adobe/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,ropik/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium,ropik/chromium,adobe/chromium,adobe/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,gavinp/chromium