Prevent a crash and add debugging code for cases where things go wrong

when trying to unload a half-crashed extension.

TEST=none
BUG=30405

Review URL: http://codereview.chromium.org/523163

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@35935 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 23 insertions, 1 deletions

diff --git a/chrome/browser/extensions/extension_process_manager.cc b/chrome/browser/extensions/extension_process_manager.cc
index 76e2a6e..3121d3c 100644
--- a/chrome/browser/extensions/extension_process_manager.cc
+++ b/chrome/browser/extensions/extension_process_manager.cc
@@ -194,6 +194,10 @@ SiteInstance* ExtensionProcessManager::GetSiteInstanceForURL(const GURL& url) {
   return browsing_instance_->GetSiteInstanceForURL(url);
 }
 
+bool ExtensionProcessManager::HasExtensionHost(ExtensionHost* host) const {
+  return all_hosts_.find(host) != all_hosts_.end();
+}
+
 void ExtensionProcessManager::Observe(NotificationType type,
                                       const NotificationSource& source,
                                       const NotificationDetails& details) {
diff --git a/chrome/browser/extensions/extension_process_manager.h b/chrome/browser/extensions/extension_process_manager.h
index f399a0b..1cfec71 100644
--- a/chrome/browser/extensions/extension_process_manager.h
+++ b/chrome/browser/extensions/extension_process_manager.h
@@ -73,6 +73,9 @@ class ExtensionProcessManager : public NotificationObserver {
   // Returns the process that the extension with the given ID is running in.
   RenderProcessHost* GetExtensionProcess(const std::string& extension_id);
 
+  // Returns true if |host| is managed by this process manager.
+  bool HasExtensionHost(ExtensionHost* host) const;
+
   // NotificationObserver:
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index e64956a..dc0c0ae 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -529,6 +529,7 @@ void ExtensionsService::CheckForExternalUpdates() {
 }
 
 void ExtensionsService::UnloadExtension(const std::string& extension_id) {
+  // Make sure the extension gets deleted after we return from this function.
   scoped_ptr<Extension> extension(
       GetExtensionByIdInternal(extension_id, true, true));
 
@@ -879,10 +880,24 @@ void ExtensionsService::Observe(NotificationType type,
       DCHECK_EQ(profile_, Source<Profile>(source).ptr());
 
       ExtensionHost* host = Details<ExtensionHost>(details).ptr();
+      // TODO(phajdan.jr): Change to DCHECK after fixing http://crbug.com/30405.
+      CHECK(profile_->GetExtensionProcessManager()->HasExtensionHost(host));
+
+      // If we hit one of these assertions it means that the host's
+      // Extension pointer became invalid (http://crbug.com/30405).
+      // TODO(phajdan.jr): Remove excessive debugging after fixing bug 30405.
+      std::string extension_id(host->extension()->id());
+      CHECK(extension_id.length() == 32U);
+      Extension* extension = GetExtensionById(extension_id, true);
+      CHECK(extension == host->extension());
+      if (!extension) {
+        NOTREACHED();
+        return;
+      }
 
       // Unload the entire extension. We want it to be in a consistent state:
       // either fully working or not loaded at all, but never half-crashed.
-      UnloadExtension(host->extension()->id());
+      UnloadExtension(extension_id);
       break;
     }