Add support for OfflinePagesDownloadBridge.

components/offline_pages/downloads/download_ui_adapter.cc

Index: components/offline_pages/downloads/download_ui_adapter.cc
diff --git a/components/offline_pages/downloads/download_ui_adapter.cc b/components/offline_pages/downloads/download_ui_adapter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..aecbf596f5156ce246e98d4be7cfdbfecc4b2541
--- /dev/null
+++ b/components/offline_pages/downloads/download_ui_adapter.cc
@@ -0,0 +1,145 @@
+// Copyright 2016 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/downloads/download_ui_adapter.h"
+
+#include "base/bind.h"
+#include "base/guid.h"
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "components/offline_pages/client_namespace_constants.h"
+#include "components/offline_pages/downloads/download_ui_item.h"
+#include "components/offline_pages/offline_page_model.h"
+
+namespace offline_pages {
+
+DownloadUIAdapter::DownloadUIAdapter(OfflinePageModel* model)
+    : model_(model),
+      is_loaded_(false),
+      weak_ptr_factory_(this) {
+}
+
+DownloadUIAdapter::~DownloadUIAdapter() { }
+
+void DownloadUIAdapter::AddObserver(Observer* observer) {
+  DCHECK(observer);
+  if (!observers_.might_have_observers())
+    LoadCache();
+  observers_.AddObserver(observer);
+  // If the items are already loaded, post the notification right away.
+  // Don't just invoke it from here to avoid reentrancy in the client.
+  if (is_loaded_) {
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&DownloadUIAdapter::NotifyItemsLoaded,
+                              weak_ptr_factory_.GetWeakPtr(),
+                              base::Unretained(observer)));
+  }
+}
+
+void DownloadUIAdapter::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+  // Once the last observer is gone, clear cached data.
+  if (!observers_.might_have_observers())
+    ClearCache();
+}
+
+void DownloadUIAdapter::OfflinePageModelLoaded(OfflinePageModel* model) {
+  // This signal is not used here.
+}
+
+void DownloadUIAdapter::OfflinePageModelChanged(OfflinePageModel* model) {
+  DCHECK(model == model_);
+  model_->GetAllPages(
+      base::Bind(&DownloadUIAdapter::OnOfflinePagesChanged,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void DownloadUIAdapter::OfflinePageDeleted(
+  int64_t offline_id, const ClientId& client_id) {
+  for(const auto& item : items_) {
+    if (item.second->guid == client_id.id) {
+      items_.erase(item.first);
+      FOR_EACH_OBSERVER(Observer, observers_, ItemDeleted(client_id.id));
+      return;
+    }
+  }
+}
+
+const DownloadUIItemsMap& DownloadUIAdapter::GetAllItems() const {
+  return items_;
+}
+
+const DownloadUIItem*
+    DownloadUIAdapter::GetItem(const std::string& guid) const {
+  DownloadUIItemsMap::const_iterator it = items_.find(guid);
+  if (it == items_.end())
+    return nullptr;
+  return (*it).second.get();
+}
+
+void DownloadUIAdapter::LoadCache() {
+  DCHECK(!is_loaded_);
+  // TODO(dimich): Add fetching from RequestQueue as well.
+  model_->AddObserver(this);
+  model_->GetAllPages(
+      base::Bind(&DownloadUIAdapter::OnOfflinePagesLoaded,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void DownloadUIAdapter::ClearCache() {
+  model_->RemoveObserver(this);
+  items_.clear();
+  is_loaded_ = false;
+}
+
+void DownloadUIAdapter::OnOfflinePagesLoaded(
+    const MultipleOfflinePageItemResult& pages) {
+  for (const auto& page : pages) {
+    if (IsVisibleInUI(page)) {
+      std::unique_ptr<DownloadUIItem> new_item(new DownloadUIItem(page));
+      DCHECK(items_.find(new_item->guid) == items_.end());

[fgorski, 2016/07/26 16:25:21]

I like the idea below:
const std::string& guid = page.client_id.id;

It would allow you to first do the DCHECK and then new up an object and put it
in the map.

[Dmitry Titov, 2016/07/26 19:56:48]

Done.

+      items_[new_item->guid] = std::move(new_item);
+    }
+  }
+  is_loaded_ = true;
+  FOR_EACH_OBSERVER(Observer, observers_, ItemsLoaded());
+}
+
+void DownloadUIAdapter::NotifyItemsLoaded(Observer* observer) {
+  if (observer && observers_.HasObserver(observer))
+    observer->ItemsLoaded();
+}
+
+// This method is only called by OPM when a single item added.
+// TODO(dimich): change OPM to have real OnPageAdded/OnPageUpdated and
+// simplify this code.
+void DownloadUIAdapter::OnOfflinePagesChanged(
+    const MultipleOfflinePageItemResult& pages) {
+  std::vector<std::string> added_guids;
+  for (const auto& page : pages) {
+    if (!IsVisibleInUI(page))  // Item should be filtered out.
+      continue;
+    const std::string& guid = page.client_id.id;
+    if (items_.find(guid) != items_.end())  // Item already exists.
+      continue;
+    std::unique_ptr<DownloadUIItem> item(new DownloadUIItem(page));
+    added_guids.push_back(guid);

[fgorski, 2016/07/26 16:25:21]

nit: Can you move this line up or down? It feels like it breaks apart 2 lines
that are much more related to each other.

[Dmitry Titov, 2016/07/26 19:56:48]

Done.

+    items_[guid] = std::move(item);
+  }
+  // Only one added page

[fgorski, 2016/07/26 16:25:21]

Interesting. Do we even need the update to be in the interface?

<Update>I just saw your comment in test. We can discuss that today</Update>

[Dmitry Titov, 2016/07/26 19:56:48]

I'd have it in interface. We will need it soon (indicating some progress or even
change in response to user actions in UI. We could add it later but it's nice to
have interfaces early even if they are not 100% implemented.

+  CHECK(added_guids.size() <= 1);
+  for (auto& guid : added_guids) {
+    const DownloadUIItem& item = *(items_.find(guid)->second.get());
+    FOR_EACH_OBSERVER(Observer, observers_, ItemAdded(item));
+  }
+}
+
+bool DownloadUIAdapter::IsVisibleInUI(const OfflinePageItem& page) {
+  // TODO(dimich): set up the right filter here.
+  return page.client_id.name_space == kAsyncNamespace &&
+         base::IsValidGUID(page.client_id.id);
+}
+
+}  // namespace offline_pages