Add onWeakCredentialsChanged observer

This CL adds OnWeakCredentialsChanged to the observer interfase in
InsecureCredentialsManager.

Bug: 1119752
Change-Id: I6619f06d06cf99113ddb05b4e12a69110b531460
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2391122
Commit-Queue: Irina Fedorova <irfedorova@google.com>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804771}

chrome/browser/extensions/api/passwords_private/password_check_delegate.cc

@@ -471,6 +471,13 @@ void PasswordCheckDelegate::OnCompromisedCredentialsChanged(
   }
 }
 
+void PasswordCheckDelegate::OnWeakCredentialsChanged(
+    InsecureCredentialsView credentials) {
+  // TODO(crbug.com/1119752): Implement this method after adding
+  // OnWeakCredentialsChanged to PasswordsPrivateEventRouter.
+  NOTIMPLEMENTED();
+}
+
 void PasswordCheckDelegate::OnStateChanged(State state) {
   if (state == State::kIdle && std::exchange(is_check_running_, false)) {
     // When the service transitions from running into idle it has finished a

chrome/browser/extensions/api/passwords_private/password_check_delegate.h

@@ -96,6 +96,13 @@ class PasswordCheckDelegate
       password_manager::InsecureCredentialsManager::CredentialsView credentials)
       override;
 
+  // password_manager::InsecureCredentialsManager::Observer:
+  // Invokes PasswordsPrivateEventRouter::OnWeakCredentialsChanged if a valid
+  // pointer can be obtained.
+  void OnWeakCredentialsChanged(
+      password_manager::InsecureCredentialsManager::CredentialsView credentials)
+      override;
+
   // password_manager::BulkLeakCheckService::Observer:
   void OnStateChanged(
       password_manager::BulkLeakCheckService::State state) override;

components/password_manager/core/browser/ui/insecure_credentials_manager.h

@@ -107,13 +107,14 @@ class InsecureCredentialsManager
   using CredentialsView = base::span<const CredentialWithPassword>;
 
   // Observer interface. Clients can implement this to get notified about
-  // changes to the list of compromised credentials. Clients can register and
-  // de-register themselves, and are expected to do so before the provider gets
-  // out of scope.
+  // changes to the list of compromised and weak credentials. Clients can
+  // register and de-register themselves, and are expected to do so before the
+  // provider gets out of scope.
   class Observer : public base::CheckedObserver {
    public:
     virtual void OnCompromisedCredentialsChanged(
         CredentialsView credentials) = 0;
+    virtual void OnWeakCredentialsChanged(CredentialsView credentials) {}
   };
 
   InsecureCredentialsManager(