Add an observer for article updates.

Define an observer that allows clients to listen to article updates.
In a subsequent CL, I will hook the webui to observe article changes.

BUG=288015

Review URL: https://codereview.chromium.org/100463005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239703 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 199 insertions, 3 deletions

diff --git a/components/dom_distiller.gypi b/components/dom_distiller.gypi
index ddc7b2e..1b6e6b4 100644
--- a/components/dom_distiller.gypi
+++ b/components/dom_distiller.gypi
@@ -76,6 +76,7 @@
             'dom_distiller/core/dom_distiller_database.h',
             'dom_distiller/core/dom_distiller_model.cc',
             'dom_distiller/core/dom_distiller_model.h',
+            'dom_distiller/core/dom_distiller_observer.h',
             'dom_distiller/core/dom_distiller_service.cc',
             'dom_distiller/core/dom_distiller_service.h',
             'dom_distiller/core/dom_distiller_store.cc',
diff --git a/components/dom_distiller/core/dom_distiller_observer.h b/components/dom_distiller/core/dom_distiller_observer.h
new file mode 100644
index 0000000..4a99f69
--- /dev/null
+++ b/components/dom_distiller/core/dom_distiller_observer.h
@@ -0,0 +1,39 @@
+// Copyright 2013 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_DOM_DISTILLER_CORE_DOM_DISTILLER_OBSERVER_H_
+#define COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_OBSERVER_H_
+
+#include <vector>
+#include "components/dom_distiller/core/article_entry.h"
+
+namespace dom_distiller {
+
+// Provides notifications for any mutations to entries of the reading list.
+class DomDistillerObserver {
+ public:
+  // An update to an article entry.
+  struct ArticleUpdate {
+    enum UpdateType {
+      ADD,
+      UPDATE,
+      REMOVE
+    };
+    std::string entry_id;
+    UpdateType update_type;
+  };
+
+  virtual void ArticleEntriesUpdated(
+      const std::vector<ArticleUpdate>& updates) = 0;
+
+ protected:
+  DomDistillerObserver() {}
+  virtual ~DomDistillerObserver() {}
+
+  DISALLOW_COPY_AND_ASSIGN(DomDistillerObserver);
+};
+
+}  // namespace dom_distiller
+
+#endif  // COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_OBSERVER_H_
diff --git a/components/dom_distiller/core/dom_distiller_service.cc b/components/dom_distiller/core/dom_distiller_service.cc
index fb2b380..35f8203 100644
--- a/components/dom_distiller/core/dom_distiller_service.cc
+++ b/components/dom_distiller/core/dom_distiller_service.cc
@@ -144,4 +144,14 @@ void DomDistillerService::AddDistilledPageToList(const ArticleEntry& entry,
   store_->AddEntry(entry);
 }
 
+void DomDistillerService::AddObserver(DomDistillerObserver* observer) {
+  DCHECK(observer);
+  store_->AddObserver(observer);
+}
+
+void DomDistillerService::RemoveObserver(DomDistillerObserver* observer) {
+  DCHECK(observer);
+  store_->RemoveObserver(observer);
+}
+
 }  // namespace dom_distiller
diff --git a/components/dom_distiller/core/dom_distiller_service.h b/components/dom_distiller/core/dom_distiller_service.h
index a75ba70..fc27d35 100644
--- a/components/dom_distiller/core/dom_distiller_service.h
+++ b/components/dom_distiller/core/dom_distiller_service.h
@@ -20,10 +20,11 @@ namespace dom_distiller {
 
 class DistilledPageProto;
 class DistillerFactory;
+class DomDistillerObserver;
 class DomDistillerStoreInterface;
 class TaskTracker;
-class ViewRequestDelegate;
 class ViewerHandle;
+class ViewRequestDelegate;
 
 // Provide a view of the article list and ways of interacting with it.
 class DomDistillerService {
@@ -55,6 +56,9 @@ class DomDistillerService {
   scoped_ptr<ViewerHandle> ViewUrl(ViewRequestDelegate* delegate,
                                    const GURL& url);
 
+  void AddObserver(DomDistillerObserver* observer);
+  void RemoveObserver(DomDistillerObserver* observer);
+
  private:
   void CancelTask(TaskTracker* task);
   void AddDistilledPageToList(const ArticleEntry& entry,
diff --git a/components/dom_distiller/core/dom_distiller_service_unittest.cc b/components/dom_distiller/core/dom_distiller_service_unittest.cc
index 6770b3f..a017eab 100644
--- a/components/dom_distiller/core/dom_distiller_service_unittest.cc
+++ b/components/dom_distiller/core/dom_distiller_service_unittest.cc
@@ -91,6 +91,9 @@ class FakeDomDistillerStore : public DomDistillerStoreInterface {
     return NULL;
   }
 
+  virtual void AddObserver(DomDistillerObserver* observer) OVERRIDE {}
+  virtual void RemoveObserver(DomDistillerObserver* observer) OVERRIDE {}
+
  private:
   DomDistillerModel model_;
 };
diff --git a/components/dom_distiller/core/dom_distiller_store.cc b/components/dom_distiller/core/dom_distiller_store.cc
index 72d2470..ef585d0 100644
--- a/components/dom_distiller/core/dom_distiller_store.cc
+++ b/components/dom_distiller/core/dom_distiller_store.cc
@@ -121,6 +121,14 @@ bool DomDistillerStore::RemoveEntry(const ArticleEntry& entry) {
   return true;
 }
 
+void DomDistillerStore::AddObserver(DomDistillerObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void DomDistillerStore::RemoveObserver(DomDistillerObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
 std::vector<ArticleEntry> DomDistillerStore::GetEntries() const {
   return model_.GetEntries();
 }
@@ -168,11 +176,45 @@ SyncError DomDistillerStore::ProcessSyncChanges(
   return SyncError();
 }
 
+void DomDistillerStore::NotifyObservers(const syncer::SyncChangeList& changes) {
+  if (observers_.might_have_observers() && changes.size() > 0) {
+    std::vector<DomDistillerObserver::ArticleUpdate> article_changes;
+    for (SyncChangeList::const_iterator it = changes.begin();
+         it != changes.end();
+         ++it) {
+      DomDistillerObserver::ArticleUpdate article_update;
+      switch (it->change_type()) {
+        case SyncChange::ACTION_ADD:
+          article_update.update_type = DomDistillerObserver::ArticleUpdate::ADD;
+          break;
+        case SyncChange::ACTION_UPDATE:
+          article_update.update_type =
+              DomDistillerObserver::ArticleUpdate::UPDATE;
+          break;
+        case SyncChange::ACTION_DELETE:
+          article_update.update_type =
+              DomDistillerObserver::ArticleUpdate::REMOVE;
+          break;
+        case SyncChange::ACTION_INVALID:
+          NOTREACHED();
+          break;
+      }
+      const ArticleEntry& entry = GetEntryFromChange(*it);
+      article_update.entry_id = entry.entry_id();
+      article_changes.push_back(article_update);
+    }
+    FOR_EACH_OBSERVER(DomDistillerObserver,
+                      observers_,
+                      ArticleEntriesUpdated(article_changes));
+  }
+}
+
 void DomDistillerStore::ApplyChangesToModel(
     const SyncChangeList& changes,
     SyncChangeList* changes_applied,
     SyncChangeList* changes_missing) {
   model_.ApplyChangesToModel(changes, changes_applied, changes_missing);
+  NotifyObservers(*changes_applied);
 }
 
 void DomDistillerStore::OnDatabaseInit(bool success) {
diff --git a/components/dom_distiller/core/dom_distiller_store.h b/components/dom_distiller/core/dom_distiller_store.h
index d61b451..4328853 100644
--- a/components/dom_distiller/core/dom_distiller_store.h
+++ b/components/dom_distiller/core/dom_distiller_store.h
@@ -9,9 +9,11 @@
 
 #include "base/containers/hash_tables.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "components/dom_distiller/core/article_entry.h"
 #include "components/dom_distiller/core/dom_distiller_database.h"
 #include "components/dom_distiller/core/dom_distiller_model.h"
+#include "components/dom_distiller/core/dom_distiller_observer.h"
 #include "sync/api/sync_change.h"
 #include "sync/api/sync_data.h"
 #include "sync/api/sync_error.h"
@@ -47,8 +49,9 @@ class DomDistillerStoreInterface {
   // Gets a copy of all the current entries.
   virtual std::vector<ArticleEntry> GetEntries() const = 0;
 
-  // TODO(cjhopman): This should have a way to observe changes to the underlying
-  // model.
+  virtual void AddObserver(DomDistillerObserver* observer) = 0;
+
+  virtual void RemoveObserver(DomDistillerObserver* observer) = 0;
 };
 
 // Implements syncing/storing of DomDistiller entries. This keeps three
@@ -91,6 +94,8 @@ class DomDistillerStore : public syncer::SyncableService,
                             ArticleEntry* entry) OVERRIDE;
   virtual bool GetEntryByUrl(const GURL& url, ArticleEntry* entry) OVERRIDE;
   virtual std::vector<ArticleEntry> GetEntries() const OVERRIDE;
+  virtual void AddObserver(DomDistillerObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(DomDistillerObserver* observer) OVERRIDE;
 
   // syncer::SyncableService implementation.
   virtual syncer::SyncMergeResult MergeDataAndStartSyncing(
@@ -131,10 +136,13 @@ class DomDistillerStore : public syncer::SyncableService,
                            syncer::SyncChangeList* changes_applied,
                            syncer::SyncChangeList* changes_missing);
 
+  void NotifyObservers(const syncer::SyncChangeList& changes);
+
   scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
   scoped_ptr<syncer::SyncErrorFactory> error_factory_;
   scoped_ptr<DomDistillerDatabaseInterface> database_;
   bool database_loaded_;
+  ObserverList<DomDistillerObserver> observers_;
 
   DomDistillerModel model_;
 
diff --git a/components/dom_distiller/core/dom_distiller_store_unittest.cc b/components/dom_distiller/core/dom_distiller_store_unittest.cc
index b1da8a0..09ea61b 100644
--- a/components/dom_distiller/core/dom_distiller_store_unittest.cc
+++ b/components/dom_distiller/core/dom_distiller_store_unittest.cc
@@ -192,6 +192,35 @@ ArticleEntry GetSampleEntry(int id) {
   return entries[id % 9];
 }
 
+class FakeDistillerObserver : public DomDistillerObserver {
+ public:
+  MOCK_METHOD1(ArticleEntriesUpdated, void(const std::vector<ArticleUpdate>&));
+  virtual ~FakeDistillerObserver() {}
+};
+
+MATCHER_P(AreUpdatesEqual, expected_updates, "") {
+  if (arg.size() != expected_updates.size())
+    return false;
+  std::vector<DomDistillerObserver::ArticleUpdate>::const_iterator expected,
+      actual;
+  for (expected = expected_updates.begin(), actual = arg.begin();
+       expected != expected_updates.end();
+       ++expected, ++actual) {
+    if (expected->entry_id != actual->entry_id) {
+      *result_listener << " Mismatched entry id. Expected: "
+                       << expected->entry_id << " actual: " << actual->entry_id;
+      return false;
+    }
+    if (expected->update_type != actual->update_type) {
+      *result_listener << " Mismatched update. Expected: "
+                       << expected->update_type
+                       << " actual: " << actual->update_type;
+      return false;
+    }
+  }
+  return true;
+}
+
 }  // namespace
 
 class DomDistillerStoreTest : public testing::Test {
@@ -488,4 +517,64 @@ TEST_F(DomDistillerStoreTest, TestSyncMergeWithSecondDomDistillerStore) {
   EXPECT_TRUE(AreEntriesEqual(other_store->GetEntries(), expected_model));
 }
 
+TEST_F(DomDistillerStoreTest, TestObserver) {
+  CreateStore();
+  FakeDistillerObserver observer;
+  store_->AddObserver(&observer);
+  fake_db_->InitCallback(true);
+  fake_db_->LoadCallback(true);
+  std::vector<DomDistillerObserver::ArticleUpdate> expected_updates;
+  DomDistillerObserver::ArticleUpdate update;
+  update.entry_id = GetSampleEntry(0).entry_id();
+  update.update_type = DomDistillerObserver::ArticleUpdate::ADD;
+  expected_updates.push_back(update);
+  EXPECT_CALL(observer,
+              ArticleEntriesUpdated(AreUpdatesEqual(expected_updates)));
+  store_->AddEntry(GetSampleEntry(0));
+
+  expected_updates.clear();
+  update.entry_id = GetSampleEntry(1).entry_id();
+  update.update_type = DomDistillerObserver::ArticleUpdate::ADD;
+  expected_updates.push_back(update);
+  EXPECT_CALL(observer,
+              ArticleEntriesUpdated(AreUpdatesEqual(expected_updates)));
+  store_->AddEntry(GetSampleEntry(1));
+
+  expected_updates.clear();
+  update.entry_id = GetSampleEntry(0).entry_id();
+  update.update_type = DomDistillerObserver::ArticleUpdate::REMOVE;
+  expected_updates.clear();
+  expected_updates.push_back(update);
+  EXPECT_CALL(observer,
+              ArticleEntriesUpdated(AreUpdatesEqual(expected_updates)));
+  store_->RemoveEntry(GetSampleEntry(0));
+
+  // Add entry_id = 3 and update entry_id = 1.
+  expected_updates.clear();
+  SyncDataList change_data;
+  change_data.push_back(CreateSyncData(GetSampleEntry(3)));
+  ArticleEntry updated_entry(GetSampleEntry(1));
+  updated_entry.set_title("changed_title");
+  change_data.push_back(CreateSyncData(updated_entry));
+  update.entry_id = GetSampleEntry(3).entry_id();
+  update.update_type = DomDistillerObserver::ArticleUpdate::ADD;
+  expected_updates.push_back(update);
+  update.entry_id = GetSampleEntry(1).entry_id();
+  update.update_type = DomDistillerObserver::ArticleUpdate::UPDATE;
+  expected_updates.push_back(update);
+
+  EXPECT_CALL(observer,
+              ArticleEntriesUpdated(AreUpdatesEqual(expected_updates)));
+
+  FakeSyncErrorFactory* fake_error_factory = new FakeSyncErrorFactory();
+  EntryMap fake_model;
+  FakeSyncChangeProcessor* fake_sync_change_processor =
+      new FakeSyncChangeProcessor(&fake_model);
+  store_->MergeDataAndStartSyncing(
+      kDomDistillerModelType,
+      change_data,
+      make_scoped_ptr<SyncChangeProcessor>(fake_sync_change_processor),
+      make_scoped_ptr<SyncErrorFactory>(fake_error_factory));
+}
+
 }  // namespace dom_distiller