[Passwords] Introduce CompromisedCredentialsReader

This CL only introduce the simplest version of the reader which handles
only one store.

Follow-up CL will wire it up to the rest of the code, and then make it
handle multiple stores.

Bug: 1108422
Change-Id: If5202f5112cb841bd1c3ac65b37b5a1fa0eade4e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2367065
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800538}

components/password_manager/core/browser/BUILD.gn

@@ -230,6 +230,8 @@ static_library("browser") {
     "ui/bulk_leak_check_service_adapter.h",
     "ui/compromised_credentials_manager.cc",
     "ui/compromised_credentials_manager.h",
+    "ui/compromised_credentials_reader.cc",
+    "ui/compromised_credentials_reader.h",
     "ui/credential_provider_interface.h",
     "ui/credential_utils.h",
     "ui/export_flow.h",

components/password_manager/core/browser/ui/compromised_credentials_reader.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/password_manager/core/browser/ui/compromised_credentials_reader.h"
+
+namespace password_manager {
+CompromisedCredentialsReader::CompromisedCredentialsReader(PasswordStore* store)
+    : store_(store) {
+  DCHECK(store_);
+  observed_password_store_.Add(store_);
+}
+
+CompromisedCredentialsReader::~CompromisedCredentialsReader() = default;
+
+void CompromisedCredentialsReader::Init() {
+  store_->GetAllCompromisedCredentials(this);
+}
+
+void CompromisedCredentialsReader::OnCompromisedCredentialsChanged() {
+  // Cancel ongoing requests to the password store and issue a new request.
+  cancelable_task_tracker()->TryCancelAll();
+  store_->GetAllCompromisedCredentials(this);
+}
+
+void CompromisedCredentialsReader::OnGetCompromisedCredentials(
+    std::vector<CompromisedCredentials> compromised_credentials) {
+  for (auto& observer : observers_)
+    observer.OnCompromisedCredentialsChanged(compromised_credentials);
+}
+
+void CompromisedCredentialsReader::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void CompromisedCredentialsReader::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+}  // namespace password_manager

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

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_UI_COMPROMISED_CREDENTIALS_READER_H_
+#define COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_UI_COMPROMISED_CREDENTIALS_READER_H_
+
+#include "base/observer_list.h"
+#include "base/scoped_observer.h"
+#include "components/password_manager/core/browser/compromised_credentials_consumer.h"
+#include "components/password_manager/core/browser/password_store.h"
+
+namespace password_manager {
+// This class is responsible for reading and listening to change in the
+// compormised credentials in the underlying password stores.
+class CompromisedCredentialsReader
+    : public PasswordStore::DatabaseCompromisedCredentialsObserver,
+      public CompromisedCredentialsConsumer {
+ public:
+  // 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.
+  class Observer : public base::CheckedObserver {
+   public:
+    virtual void OnCompromisedCredentialsChanged(
+        const std::vector<CompromisedCredentials>& compromised_credentials) = 0;
+  };
+
+  // |store| cannot be null, and must outlive this class.
+  explicit CompromisedCredentialsReader(PasswordStore* store);
+  CompromisedCredentialsReader(const CompromisedCredentialsReader&) = delete;
+  CompromisedCredentialsReader& operator=(const CompromisedCredentialsReader&) =
+      delete;
+  ~CompromisedCredentialsReader() override;
+
+  void Init();
+
+  // Allows clients and register and de-register themselves.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ private:
+  // PasswordStore::DatabaseCompromisedCredentialsObserver:
+  void OnCompromisedCredentialsChanged() override;
+
+  // CompromisedCredentialsConsumer:
+  void OnGetCompromisedCredentials(
+      std::vector<CompromisedCredentials> compromised_credentials) override;
+
+  // The password store containing the compromised credentials. It must outlive
+  // this class.
+  PasswordStore* store_;
+
+  // A scoped observer for |store_| to listen changes related to
+  // CompromisedCredentials only.
+  ScopedObserver<PasswordStore,
+                 PasswordStore::DatabaseCompromisedCredentialsObserver,
+                 &PasswordStore::AddDatabaseCompromisedCredentialsObserver,
+                 &PasswordStore::RemoveDatabaseCompromisedCredentialsObserver>
+      observed_password_store_{this};
+
+  base::ObserverList<Observer, /*check_empty=*/true> observers_;
+};
+
+}  // namespace password_manager
+
+#endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_UI_COMPROMISED_CREDENTIALS_READER_H_