Fix early prerender cancellation not working with PlzNavigate.

With PlzNavigate the navigation starts in the browser, so LaunchAppWithUrl cancels the prerender before we get the PrerenderHostMsg_AddLinkRelPrerender IPC from the renderer. Fix this by noticing that the prerender was already cancelled when the IPC arrives.

This fixes
PlatformAppUrlRedirectorBrowserTest.PrerenderedClickInTabIntercepted
with PlzNavigate.

BUG=504347

Review-Url: https://codereview.chromium.org/2554573012
Cr-Commit-Position: refs/heads/master@{#437633}

chrome/browser/prerender/prerender_contents.h

@@ -235,6 +235,10 @@ class PrerenderContents : public content::NotificationObserver,
   // Increments the number of bytes fetched over the network for this prerender.
   void AddNetworkBytes(int64_t bytes);
 
+  bool prerendering_has_been_cancelled() const {
+    return prerendering_has_been_cancelled_;
+  }
+
  protected:
   PrerenderContents(PrerenderManager* prerender_manager,
                     Profile* profile,
@@ -263,10 +267,6 @@ class PrerenderContents : public content::NotificationObserver,
     return notification_registrar_;
   }
 
-  bool prerendering_has_been_cancelled() const {
-    return prerendering_has_been_cancelled_;
-  }
-
   content::WebContents* CreateWebContents(
       content::SessionStorageNamespace* session_storage_namespace);
 

chrome/browser/prerender/prerender_handle.cc

@@ -48,7 +48,8 @@ void PrerenderHandle::OnCancel() {
 
 bool PrerenderHandle::IsPrerendering() const {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  return prerender_data_.get() != nullptr;
+  return prerender_data_.get() != nullptr &&
+      !prerender_data_->contents()->prerendering_has_been_cancelled();
 }
 
 bool PrerenderHandle::IsFinishedLoading() const {

chrome/browser/prerender/prerender_link_manager.cc

@@ -392,16 +392,20 @@ void PrerenderLinkManager::StartPrerenders() {
       continue;
     }
 
-    // We have successfully started a new prerender.
-    (*i)->handle = handle.release();
-    ++total_started_prerender_count;
-    (*i)->handle->SetObserver(this);
-    if ((*i)->handle->IsPrerendering())
+    if (handle->IsPrerendering()) {
+      // We have successfully started a new prerender.
+      (*i)->handle = handle.release();
+      ++total_started_prerender_count;
+      (*i)->handle->SetObserver(this);
       OnPrerenderStart((*i)->handle);
-    RecordLinkManagerStarting((*i)->rel_types);
-
-    running_launcher_and_render_view_routes.insert(
-        launcher_and_render_view_route);
+      RecordLinkManagerStarting((*i)->rel_types);
+      running_launcher_and_render_view_routes.insert(
+          launcher_and_render_view_route);
+    } else {
+      Send((*i)->launcher_child_id,
+          new PrerenderMsg_OnPrerenderStop((*i)->prerender_id));
+      prerenders_.erase(*i);
+    }
   }
 }
 
@@ -522,7 +526,7 @@ void PrerenderLinkManager::OnPrerenderStop(
     return;
 
   Send(prerender->launcher_child_id,
-       new PrerenderMsg_OnPrerenderStop(prerender->prerender_id));
+      new PrerenderMsg_OnPrerenderStop(prerender->prerender_id));
   RemovePrerender(prerender);
   StartPrerenders();
 }