[Offline] Creates metadata store interface for offline pages

Offline pages metadata store:
* Creates interface for the store
* The following actions are available on the store:
  - AddOfflinePage,
  - RemoveOfflinePage,
  - Load,
* Updates to the components_unittests to include offline
  pages

BUG=491352

Review URL: https://codereview.chromium.org/1160283003

Cr-Commit-Position: refs/heads/master@{#333697}

9 files changed, 170 insertions, 3 deletions

diff --git a/components/BUILD.gn b/components/BUILD.gn
index 52379bf..8b26bd5 100644
--- a/components/BUILD.gn
+++ b/components/BUILD.gn
@@ -289,6 +289,7 @@ test("components_unittests") {
     "//components/login:unit_tests",
     "//components/metrics:unit_tests",
     "//components/mime_util:unit_tests",
+    "//components/offline_pages:unit_tests",
     "//components/omnibox:unit_tests",
     "//components/packed_ct_ev_whitelist:unit_tests",
     "//components/undo:unit_tests",
diff --git a/components/components_tests.gyp b/components/components_tests.gyp
index 303f10d..1cdfd6e 100644
--- a/components/components_tests.gyp
+++ b/components/components_tests.gyp
@@ -330,6 +330,9 @@
     'network_time_unittest_sources': [
       'network_time/network_time_tracker_unittest.cc',
     ],
+    'offline_page_unittest_sources': [
+      'offline_pages/offline_page_model_unittest.cc',
+    ],
     'omnibox_unittest_sources': [
       'omnibox/answers_cache_unittest.cc',
       'omnibox/autocomplete_input_unittest.cc',
@@ -694,6 +697,7 @@
         '<@(metrics_unittest_sources)',
         '<@(mime_util_unittest_sources)',
         '<@(network_time_unittest_sources)',
+        '<@(offline_page_unittest_sources)',
         '<@(omnibox_unittest_sources)',
         '<@(os_crypt_unittest_sources)',
         '<@(packed_ct_ev_whitelist_unittest_sources)',
@@ -796,6 +800,7 @@
         'components.gyp:metrics_profiler',
         'components.gyp:metrics_test_support',
         'components.gyp:network_time',
+        'components.gyp:offline_pages',
         'components.gyp:omnibox',
         'components.gyp:omnibox_test_support',
         'components.gyp:os_crypt',
diff --git a/components/offline_pages.gypi b/components/offline_pages.gypi
index 4afb2fc..3f217ed 100644
--- a/components/offline_pages.gypi
+++ b/components/offline_pages.gypi
@@ -22,6 +22,8 @@
         'offline_pages/offline_page_item.h',
         'offline_pages/offline_page_model.cc',
         'offline_pages/offline_page_model.h',
+        'offline_pages/offline_page_metadata_store.cc',
+        'offline_pages/offline_page_metadata_store.h',
       ],
     },
   ],
diff --git a/components/offline_pages/BUILD.gn b/components/offline_pages/BUILD.gn
index 17c32e9..e4de8cc 100644
--- a/components/offline_pages/BUILD.gn
+++ b/components/offline_pages/BUILD.gn
@@ -2,11 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# GYP: //components/offline_pages.gypi:offline_pages'
+# GYP: //components/offline_pages.gypi:offline_pages
 static_library("offline_pages") {
   sources = [
     "offline_page_item.cc",
     "offline_page_item.h",
+    "offline_page_metadata_store.cc",
+    "offline_page_metadata_store.h",
     "offline_page_model.cc",
     "offline_page_model.h",
   ]
@@ -18,3 +20,15 @@ static_library("offline_pages") {
     "//url",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "offline_page_model_unittest.cc",
+  ]
+
+  deps = [
+    ":offline_pages",
+    "//testing/gtest",
+  ]
+}
diff --git a/components/offline_pages/offline_page_metadata_store.cc b/components/offline_pages/offline_page_metadata_store.cc
new file mode 100644
index 0000000..e5cf058
--- /dev/null
+++ b/components/offline_pages/offline_page_metadata_store.cc
@@ -0,0 +1,15 @@
+// Copyright 2015 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/offline_pages/offline_page_metadata_store.h"
+
+namespace offline_pages {
+
+OfflinePageMetadataStore::OfflinePageMetadataStore() {
+}
+
+OfflinePageMetadataStore::~OfflinePageMetadataStore() {
+}
+
+}  // namespace offline_pages
diff --git a/components/offline_pages/offline_page_metadata_store.h b/components/offline_pages/offline_page_metadata_store.h
new file mode 100644
index 0000000..6d5cc07
--- /dev/null
+++ b/components/offline_pages/offline_page_metadata_store.h
@@ -0,0 +1,48 @@
+// Copyright 2015 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_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_H_
+#define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_H_
+
+#include <vector>
+
+#include "base/callback.h"
+
+class GURL;
+
+namespace offline_pages {
+
+struct OfflinePageItem;
+
+// OfflinePageMetadataStore keeps metadata for the offline pages.
+// Ability to create multiple instances of the store as well as behavior of
+// asynchronous operations when the object is being destroyed, before such
+// operation finishes will depend on implementation. It should be possbile to
+// issue multiple asynchronous operations in parallel.
+class OfflinePageMetadataStore {
+ public:
+  typedef base::Callback<void(bool, const std::vector<OfflinePageItem>&)>
+      LoadCallback;
+  typedef base::Callback<void(bool)> UpdateCallback;
+
+  OfflinePageMetadataStore();
+  virtual ~OfflinePageMetadataStore();
+
+  // Get all of the offline pages from the store.
+  virtual void Load(const LoadCallback& callback) = 0;
+
+  // Asynchronously adds offline page metadata to the store for a given URL.
+  // Result of the update is passed in callback.
+  virtual void AddOfflinePage(const OfflinePageItem& offline_page,
+                              const UpdateCallback& callback) = 0;
+
+  // Asynchronously removes offline page metadata from the store.
+  // Result of the update is passed in callback.
+  virtual void RemoveOfflinePage(const GURL& page_url,
+                                 const UpdateCallback& callback) = 0;
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_METADATA_STORE_H_
diff --git a/components/offline_pages/offline_page_model.cc b/components/offline_pages/offline_page_model.cc
index afb51c9..5fd54d0 100644
--- a/components/offline_pages/offline_page_model.cc
+++ b/components/offline_pages/offline_page_model.cc
@@ -6,11 +6,13 @@
 
 #include "base/logging.h"
 #include "components/offline_pages/offline_page_item.h"
+#include "components/offline_pages/offline_page_metadata_store.h"
 #include "url/gurl.h"
 
 namespace offline_pages {
 
-OfflinePageModel::OfflinePageModel() {
+OfflinePageModel::OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store)
+    : store_(store.Pass()) {
 }
 
 OfflinePageModel::~OfflinePageModel() {
@@ -29,4 +31,8 @@ std::vector<OfflinePageItem> OfflinePageModel::GetAllOfflinePages() {
   return std::vector<OfflinePageItem>();
 }
 
+OfflinePageMetadataStore* OfflinePageModel::GetStoreForTesting() {
+  return store_.get();
+}
+
 }  // namespace offline_pages
diff --git a/components/offline_pages/offline_page_model.h b/components/offline_pages/offline_page_model.h
index 7e57a14..d32ace1 100644
--- a/components/offline_pages/offline_page_model.h
+++ b/components/offline_pages/offline_page_model.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "components/keyed_service/core/keyed_service.h"
 
 class GURL;
@@ -15,12 +16,13 @@ class GURL;
 namespace offline_pages {
 
 struct OfflinePageItem;
+class OfflinePageMetadataStore;
 
 // Serivce for saving pages offline, storing the offline copy and metadata, and
 // retrieving them upon request.
 class OfflinePageModel : public KeyedService {
  public:
-  OfflinePageModel();
+  explicit OfflinePageModel(scoped_ptr<OfflinePageMetadataStore> store);
   ~OfflinePageModel() override;
 
   // KeyedService:
@@ -32,7 +34,13 @@ class OfflinePageModel : public KeyedService {
   // Gets a set of all offline pages metadata.
   std::vector<OfflinePageItem> GetAllOfflinePages();
 
+  // Methods for testing only:
+  OfflinePageMetadataStore* GetStoreForTesting();
+
  private:
+  // Persistent store for offline page metadata.
+  scoped_ptr<OfflinePageMetadataStore> store_;
+
   DISALLOW_COPY_AND_ASSIGN(OfflinePageModel);
 };
 
diff --git a/components/offline_pages/offline_page_model_unittest.cc b/components/offline_pages/offline_page_model_unittest.cc
new file mode 100644
index 0000000..b6119ef
--- /dev/null
+++ b/components/offline_pages/offline_page_model_unittest.cc
@@ -0,0 +1,68 @@
+// Copyright 2015 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/offline_pages/offline_page_model.h"
+
+#include "components/offline_pages/offline_page_metadata_store.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+namespace {
+
+class OfflinePageTestStore : public OfflinePageMetadataStore {
+ public:
+  ~OfflinePageTestStore() override;
+
+  // OfflinePageMetadataStore overrides:
+  void Load(const LoadCallback& callback) override;
+  void AddOfflinePage(const OfflinePageItem& offline_page,
+                      const UpdateCallback& callback) override;
+  void RemoveOfflinePage(const GURL& page_url,
+                         const UpdateCallback& callback) override;
+};
+
+OfflinePageTestStore::~OfflinePageTestStore() {
+}
+
+void OfflinePageTestStore::Load(const LoadCallback& callback) {
+}
+
+void OfflinePageTestStore::AddOfflinePage(const OfflinePageItem& offline_page,
+                                          const UpdateCallback& callback) {
+}
+
+void OfflinePageTestStore::RemoveOfflinePage(const GURL& page_url,
+                                             const UpdateCallback& callback) {
+}
+
+class OfflinePageModelTest : public testing::Test {
+ public:
+  OfflinePageModelTest();
+  ~OfflinePageModelTest() override;
+
+  scoped_ptr<OfflinePageMetadataStore> BuildStore();
+};
+
+OfflinePageModelTest::OfflinePageModelTest() {
+}
+
+OfflinePageModelTest::~OfflinePageModelTest() {
+}
+
+scoped_ptr<OfflinePageMetadataStore> OfflinePageModelTest::BuildStore() {
+  return scoped_ptr<OfflinePageMetadataStore>(new OfflinePageTestStore());
+}
+
+TEST_F(OfflinePageModelTest, Initialize) {
+  scoped_ptr<OfflinePageMetadataStore> store = BuildStore();
+  OfflinePageMetadataStore* store_ptr = store.get();
+  OfflinePageModel model(store.Pass());
+  EXPECT_EQ(store_ptr, model.GetStoreForTesting());
+}
+
+}  // namespace
+
+}  // namespace offline_pages