Make PrerenderHandle an observer of PrerenderContents.

chrome/browser/predictors/autocomplete_action_predictor.cc

Index: chrome/browser/predictors/autocomplete_action_predictor.cc
diff --git a/chrome/browser/predictors/autocomplete_action_predictor.cc b/chrome/browser/predictors/autocomplete_action_predictor.cc
index 291bbd67c8eafc5285351e072868d818beacceaa..aff4da38dabeb5f8ddf3bf92d60f5ea7feec2982 100644
--- a/chrome/browser/predictors/autocomplete_action_predictor.cc
+++ b/chrome/browser/predictors/autocomplete_action_predictor.cc
@@ -100,8 +100,7 @@ AutocompleteActionPredictor::~AutocompleteActionPredictor() {
     main_profile_predictor_->incognito_predictor_ = NULL;
   else if (incognito_predictor_)
     incognito_predictor_->main_profile_predictor_ = NULL;
-  if (prerender_handle_.get())
-    prerender_handle_->OnCancel();
+  prerender_handle_.reset();

[mmenke, 2012/12/13 18:27:16]

Since it automatically is cancelled on destruction, and we aren't observing the
handle, can we just delete this line?

[gavinp, 2012/12/13 20:45:34]

I had to remove that auto delete on destruction behaviour so that we'd be less
leaky in the link manager on channel close... Whoops. That will be in the next
upload of the events CL.

 }
 
 void AutocompleteActionPredictor::RegisterTransitionalMatches(