Fix use after free in SearchProviderInstallData GoogleURLObserver.

Follow-up to r246358.

BUG=338341
R=avi@chromium.org
TBR=pkasting@chromium.org

Review URL: https://codereview.chromium.org/137833009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247898 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/search_engines/search_provider_install_data.cc

@@ -146,6 +146,7 @@ void GoogleURLObserver::Observe(int type,
 
 void GoogleURLObserver::RenderProcessHostDestroyed(
     content::RenderProcessHost* host) {
+  host->RemoveObserver(this);
   delete this;
 }