Migrate ChromeExtensionTestNotificationObserver off of Notification Service

Note these intentional changes:
1. Since NotificationSet is essentially polling for a change in the
result of the predicate passed to it instead of waiting for a
specific event, we don't bother having callers specify which notifications to check the predicate on.
2. Observing render process termination appears to be redundant with
OnExtensionFrameUnregistered for the purposes of this class, so we
no longer explicitly observe the former.
3. It does not appear necessary to observe all sources, so we now
only observe any existing extension related WebContents at the
creation of the observer and then any WebContents created afterwards.

Bug: 1174764, 357627
Change-Id: I64ac3d2810fc49bb5ef2ebc18cad8c9f8fd5f404
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4654944
Auto-Submit: Kevin McNee <mcnee@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Reviewed-by: David Bertoni <dbertoni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1184319}

diff --git a/extensions/test/extension_test_notification_observer.h b/extensions/test/extension_test_notification_observer.h
index 1e5dd85..63f285b 100644
--- a/extensions/test/extension_test_notification_observer.h
+++ b/extensions/test/extension_test_notification_observer.h

@@ -13,14 +13,12 @@
 #include "base/functional/callback.h"
 #include "base/memory/raw_ptr.h"
 #include "base/scoped_observation.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
+#include "content/public/test/browser_test_utils.h"
 #include "extensions/browser/process_manager.h"
 #include "extensions/browser/process_manager_observer.h"
 
 namespace content {
 class BrowserContext;
-class NotificationDetails;
 class WebContents;
 }
 
@@ -39,56 +37,58 @@
   ~ExtensionTestNotificationObserver();
 
  protected:
-  class NotificationSet : public content::NotificationObserver,
-                          public extensions::ProcessManagerObserver {
+  class NotificationSet : public extensions::ProcessManagerObserver {
    public:
-    NotificationSet();
+    explicit NotificationSet(ProcessManager* manager);
 
     NotificationSet(const NotificationSet&) = delete;
     NotificationSet& operator=(const NotificationSet&) = delete;
 
     ~NotificationSet() override;
 
-    void Add(int type, const content::NotificationSource& source);
-    void Add(int type);
-    void AddExtensionFrameUnregistration(extensions::ProcessManager* manager);
-    void AddWebContentsDestroyed(extensions::ProcessManager* manager);
-
-    // Notified any time an Add()ed notification is received.
+    // Notified any time a notification is received.
     // The details of the notification are dropped.
     base::RepeatingClosureList& closure_list() { return closure_list_; }
 
    private:
     class ForwardingWebContentsObserver;
 
-    // content::NotificationObserver:
-    void Observe(int type,
-                 const content::NotificationSource& source,
-                 const content::NotificationDetails& details) override;
-
     // extensions::ProcessManagerObserver:
     void OnExtensionFrameUnregistered(
         const std::string& extension_id,
         content::RenderFrameHost* render_frame_host) override;
 
+    void OnWebContentsCreated(content::WebContents* web_contents);
+    void StartObservingWebContents(content::WebContents* web_contents);
+
+    void DidStopLoading(content::WebContents* web_contents);
     void WebContentsDestroyed(content::WebContents* web_contents);
 
-    content::NotificationRegistrar notification_registrar_;
     base::RepeatingClosureList closure_list_;
+
     base::ScopedObservation<extensions::ProcessManager,
                             extensions::ProcessManagerObserver>
         process_manager_observation_{this};
 
+    base::CallbackListSubscription web_contents_creation_subscription_ =
+        content::RegisterWebContentsCreationCallback(
+            base::BindRepeating(&NotificationSet::OnWebContentsCreated,
+                                base::Unretained(this)));
+
     std::map<content::WebContents*,
              std::unique_ptr<ForwardingWebContentsObserver>>
         web_contents_observers_;
   };
 
+  // A callback that returns true if the condition has been met and takes no
+  // arguments.
+  using ConditionCallback = base::RepeatingCallback<bool(void)>;
+
   // Wait for |condition_| to be met. |notification_set| is the set of
   // notifications to wait for and to check |condition| when observing. This
   // can be NULL if we are instead waiting for a different observer method, like
   // OnPageActionsUpdated().
-  void WaitForCondition(const base::RepeatingCallback<bool(void)>& condition,
+  void WaitForCondition(const ConditionCallback& condition,
                         NotificationSet* notification_set);
 
   // Quits the message loop if |condition_| is met.
@@ -99,7 +99,7 @@
  private:
   // The condition for which we are waiting. This should be checked in any
   // observing methods that could trigger it.
-  base::RepeatingCallback<bool(void)> condition_;
+  ConditionCallback condition_;
 
   // The closure to quit the currently-running message loop.
   base::OnceClosure quit_closure_;