Attempt at preventing a crasher.

In some cases TaskManagerResource can still be alive and pointing to a deleted WebContents, not sure how it can happen.
Now also listening for TabContent destruction notifications in case we are missing the WebContents one for some reason.

BUG=7321
Review URL: http://codereview.chromium.org/21233

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@9527 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 15 insertions, 0 deletions

diff --git a/chrome/browser/task_manager_resource_providers.cc b/chrome/browser/task_manager_resource_providers.cc
index ceb48cc..d16085e 100644
--- a/chrome/browser/task_manager_resource_providers.cc
+++ b/chrome/browser/task_manager_resource_providers.cc
@@ -146,6 +146,13 @@ void TaskManagerWebContentsResourceProvider::StartUpdating() {
                        NotificationService::AllSources());
   service->AddObserver(this, NotificationType::WEB_CONTENTS_DISCONNECTED,
                        NotificationService::AllSources());
+  // WEB_CONTENTS_DISCONNECTED should be enough to know when to remove a
+  // resource.  This is an attempt at mitigating a crasher that seem to
+  // indicate a resource is still referencing a deleted WebContents
+  // (http://crbug.com/7321).
+  service->AddObserver(this, NotificationType::TAB_CONTENTS_DESTROYED,
+                       NotificationService::AllSources());
+
 }
 
 void TaskManagerWebContentsResourceProvider::StopUpdating() {
@@ -160,6 +167,8 @@ void TaskManagerWebContentsResourceProvider::StopUpdating() {
                           NotificationService::AllSources());
   service->RemoveObserver(this, NotificationType::WEB_CONTENTS_DISCONNECTED,
                           NotificationService::AllSources());
+  service->RemoveObserver(this, NotificationType::TAB_CONTENTS_DESTROYED,
+                          NotificationService::AllSources());
 
   // Delete all the resources.
   STLDeleteContainerPairSecondPointers(resources_.begin(), resources_.end());
@@ -230,6 +239,12 @@ void TaskManagerWebContentsResourceProvider::Observe(NotificationType type,
       Remove(Source<WebContents>(source).ptr());
       Add(Source<WebContents>(source).ptr());
       break;
+    case NotificationType::TAB_CONTENTS_DESTROYED:
+      // If this DCHECK is triggered, it could explain http://crbug.com/7321.
+      DCHECK(resources_.find(Source<WebContents>(source).ptr()) ==
+             resources_.end()) << "TAB_CONTENTS_DESTROYED with no associated "
+                                  "WEB_CONTENTS_DISCONNECTED";
+      // Fall through.
     case NotificationType::WEB_CONTENTS_DISCONNECTED:
       Remove(Source<WebContents>(source).ptr());
       break;