Add observer interface to PrerenderContents.

chrome/browser/prerender/prerender_tracker.cc

Index: chrome/browser/prerender/prerender_tracker.cc
diff --git a/chrome/browser/prerender/prerender_tracker.cc b/chrome/browser/prerender/prerender_tracker.cc
index bcd95e69993d9079d90278e15d1daba87739aba8..bd122e20dda97b3376bff6c7bdb995ea52adc38e 100644
--- a/chrome/browser/prerender/prerender_tracker.cc
+++ b/chrome/browser/prerender/prerender_tracker.cc
@@ -48,14 +48,22 @@ struct RenderViewInfo {
 };
 
 PrerenderTracker::PrerenderTracker() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 }
 
 PrerenderTracker::~PrerenderTracker() {
+  DCHECK(observing_set_.empty());
 }
 
-bool PrerenderTracker::TryUse(int child_id, int route_id) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+void PrerenderTracker::AddPrerenderContents(
+    PrerenderContents* prerender_contents) {
+  DCHECK(CalledOnValidThread());
+  prerender_contents->AddObserver(this);
+  observing_set_.insert(prerender_contents);
+}
 
+bool PrerenderTracker::TryUse(int child_id, int route_id) {
+  DCHECK(CalledOnValidThread());
   return SetFinalStatus(child_id, route_id, FINAL_STATUS_USED, NULL);
 }
 
@@ -77,7 +85,8 @@ bool PrerenderTracker::TryCancelOnIOThread(
     int route_id,
     FinalStatus final_status) {
   DCHECK_NE(FINAL_STATUS_USED, final_status);
-  DCHECK(final_status >= 0 && final_status < FINAL_STATUS_MAX);
+  DCHECK_LE(0, final_status);
+  DCHECK_GT(FINAL_STATUS_MAX, final_status);
 
   if (!IsPrerenderingOnIOThread(child_id, route_id))
     return false;
@@ -91,23 +100,26 @@ bool PrerenderTracker::GetFinalStatus(int child_id, int route_id,
   base::AutoLock lock(final_status_map_lock_);
   FinalStatusMap::const_iterator final_status_it =
       final_status_map_.find(child_route_id_pair);
-  if (final_status_map_.end() == final_status_map_.find(child_route_id_pair))
+  if (final_status_map_.count(child_route_id_pair) == 0)
     return false;
   *final_status = final_status_it->second.final_status;
   return true;
 }
 
-void PrerenderTracker::OnPrerenderingStarted(
-    int child_id, int route_id, PrerenderManager* prerender_manager) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK_GE(child_id, 0);
-  DCHECK_GE(route_id, 0);
+void PrerenderTracker::OnPrerenderStart(
+    PrerenderContents* prerender_contents) {
+  DCHECK(CalledOnValidThread());
+  int child_id;
+  if (!prerender_contents->GetChildId(&child_id))
+    return;
+  int route_id;
+  if (!prerender_contents->GetRouteId(&route_id))
+    return;

[mmenke, 2012/12/04 18:59:16]

I'm perfectly happy with the current order.  However, now I think we should add
a NOTREACHED() before both return statements.

In fact...Should we even be checking the return values, except maybe in a
DCHECK?  These shouldn't fail, in release builds.  Suppose there's a chance
process creation could fail, but even in that case, don't think there's any harm
in not early-exiting.

[gavinp, 2012/12/04 22:26:07]

Done.

 
   ChildRouteIdPair child_route_id_pair(child_id, route_id);
 
   // The RenderView should not already be prerendering.
-  DCHECK(final_status_map_.end() ==
-         final_status_map_.find(child_route_id_pair));
+  DCHECK_EQ(0u, final_status_map_.count(child_route_id_pair));
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
@@ -116,13 +128,21 @@ void PrerenderTracker::OnPrerenderingStarted(
   base::AutoLock lock(final_status_map_lock_);
 
   final_status_map_.insert(
-      std::make_pair(child_route_id_pair, RenderViewInfo(prerender_manager)));
+      std::make_pair(child_route_id_pair,
+                     RenderViewInfo(prerender_contents->prerender_manager())));
 }
 
-void PrerenderTracker::OnPrerenderingFinished(int child_id, int route_id) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK_GE(child_id, 0);
-  DCHECK_GE(route_id, 0);
+void PrerenderTracker::OnPrerenderStop(
+    PrerenderContents* prerender_contents) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_EQ(1u, observing_set_.count(prerender_contents));
+  observing_set_.erase(prerender_contents);
+  int child_id;
+  if (!prerender_contents->GetChildId(&child_id))
+    return;
+  int route_id;
+  if (!prerender_contents->GetRouteId(&route_id))
+    return;

[mmenke, 2012/12/04 18:59:16]

Same as comment above.

[gavinp, 2012/12/04 22:26:07]

Done.

 
   ChildRouteIdPair child_route_id_pair(child_id, route_id);
 
@@ -178,8 +198,7 @@ bool PrerenderTracker::IsPrerenderingOnIOThread(int child_id,
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   ChildRouteIdPair child_route_id_pair(child_id, route_id);
-  return possibly_prerendering_io_thread_set_.end() !=
-         possibly_prerendering_io_thread_set_.find(child_route_id_pair);
+  return possibly_prerendering_io_thread_set_.count(child_route_id_pair) > 0;
 }
 
 void PrerenderTracker::AddPrerenderOnIOThread(