Add observer interface to PrerenderContents.

chrome/browser/prerender/prerender_tracker.h

Index: chrome/browser/prerender/prerender_tracker.h
diff --git a/chrome/browser/prerender/prerender_tracker.h b/chrome/browser/prerender/prerender_tracker.h
index f4bc1088ec4faef8b36da6f930d2873417888059..28e772f5ea54970af79f34345c733d7121e434bd 100644
--- a/chrome/browser/prerender/prerender_tracker.h
+++ b/chrome/browser/prerender/prerender_tracker.h
@@ -7,11 +7,13 @@
 
 #include <map>
 #include <set>
+#include <utility>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/non_thread_safe.h"
+#include "chrome/browser/prerender/prerender_contents.h"
 #include "chrome/browser/prerender/prerender_final_status.h"
 #include "googleurl/src/gurl.h"
 
@@ -23,17 +25,17 @@ struct RenderViewInfo;
 // PrerenderTracker is responsible for keeping track of all prerendering
 // RenderViews and their statuses.  Its list is guaranteed to be up to date
 // and can be modified on any thread.
-class PrerenderTracker {
+class PrerenderTracker : public base::NonThreadSafe,
+                         public PrerenderContents::Observer {
  public:
   PrerenderTracker();
-  ~PrerenderTracker();
+  virtual ~PrerenderTracker();
 
   // Attempts to set the status of the specified RenderViewHost to
   // FINAL_STATUS_USED.  Returns true on success.  Returns false if it has
   // already been cancelled for any reason or is no longer prerendering.
   // Can only be called only on the IO thread.  This method will not call
-  // PrerenderContents::set_final_status() on the corresponding
-  // PrerenderContents.
+  // PrerenderContents::SetFinalStatus() on the corresponding PrerenderContents.
   //
   // If it returns true, all subsequent calls to TryCancel and TryUse for the
   // RenderView will return false.
@@ -83,13 +85,12 @@ class PrerenderTracker {
 
   // Must be called when a RenderView starts prerendering, before the first
   // navigation starts to avoid any races.
-  void OnPrerenderingStarted(int child_id, int route_id,
-                             PrerenderManager* prerender_manager);
+  virtual void OnPrerenderStart(PrerenderContents* prerender_contents) OVERRIDE;
 
   // Must be called when a RenderView stops prerendering, either because the
   // RenderView was used or prerendering was cancelled and it is being
   // destroyed.
-  void OnPrerenderingFinished(int child_id, int route_id);
+  virtual void OnPrerenderStop(PrerenderContents* prerender_contents) OVERRIDE;

[mmenke, 2012/12/06 19:54:22]

optional:  While still technically accurate, not sure the comments for either of
these functions are still useful, since they're now part of the interface.

Think they're now more along the kind of things you put alongside a DCHECK.

[gavinp, 2012/12/07 17:37:04]

Done.

 
   // Attempts to set the FinalStatus of the specified RenderView to
   // |desired_final_status|.  If non-NULL, |actual_final_status| is set to the