[NTP::Push] Add Content Suggestions GCM App Handler

components/ntp_snippets/breaking_news/subscription_manager.cc

 // Copyright 2017 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/ntp_snippets/breaking_news/subscription_manager.h"
 #include "base/bind.h"
 #include "components/ntp_snippets/breaking_news/subscription_json_request.h"
 #include "components/ntp_snippets/pref_names.h"
 #include "components/prefs/pref_service.h"
 
 namespace ntp_snippets {
 
 using internal::SubscriptionJsonRequest;
 
 SubscriptionManager::SubscriptionManager(
     scoped_refptr<net::URLRequestContextGetter> url_request_context_getter,
     PrefService* pref_service,
-    const GURL& subscribe_url)
+    const GURL& subscribe_url,
+    const GURL& unsubscribe_url)
     : url_request_context_getter_(std::move(url_request_context_getter)),
       pref_service_(pref_service),
-      subscribe_url_(subscribe_url) {}
+      subscribe_url_(subscribe_url),
+      unsubscribe_url_(unsubscribe_url) {}
 
 SubscriptionManager::~SubscriptionManager() = default;
 
 void SubscriptionManager::Subscribe(const std::string& token) {
   DCHECK(!subscription_request_);
   subscription_token_ = token;
   SubscriptionJsonRequest::Builder builder;
   builder.SetToken(token)
       .SetUrlRequestContextGetter(url_request_context_getter_)
       .SetUrl(subscribe_url_);
@@ skipping 16 matching lines @@
           ntp_snippets::prefs::kContentSuggestionsSubscriptionDataToken,
           subscription_token_);
       break;
     default:
       // TODO(mamir): handle failure.
       break;
   }
 }
 
 void SubscriptionManager::Unsubscribe(const std::string& token) {
-  // TODO(mamir): Implement.
+  DCHECK(!unsubscription_request_);

[jkrcal, 2017/06/09 09:10:10]

I find this (and above) a bit subtle to use:
It is not allowed to run concurrent Subscribe / Unsubscribe requests but the
caller will never know when a request is finished.

Why DCHECK and not simply return (e.g. false)?
Is it okay to call Subscribe() before Unsubscribe() finished?

[mamir, 2017/06/09 13:52:58]

As discussed off-review, I have added 3 methods CanSubscribeNow(),
CanUnsubscribeNow(), IsSubscribed()
PTAL

+  unsubscription_token_ = token;
+  SubscriptionJsonRequest::Builder builder;
+  builder.SetToken(token)
+      .SetUrlRequestContextGetter(url_request_context_getter_)
+      .SetUrl(unsubscribe_url_);
+
+  unsubscription_request_ = builder.Build();
+  unsubscription_request_->Start(base::BindOnce(
+      &SubscriptionManager::DidUnsubscribe, base::Unretained(this)));
+}
+
+void SubscriptionManager::DidUnsubscribe(const ntp_snippets::Status& status) {
+  unsubscription_request_.reset();
+
+  switch (status.code) {
+    case ntp_snippets::StatusCode::SUCCESS:
+      // In case of successful unsubscription, clear the previously stored data.
+      // TODO(mamir): clear stored region and language.
+      pref_service_->ClearPref(
+          ntp_snippets::prefs::kContentSuggestionsSubscriptionDataToken);
+      break;
+    default:
+      // TODO(mamir): handle failure.
+      break;
+  }
 }
 
 void SubscriptionManager::RegisterProfilePrefs(PrefRegistrySimple* registry) {
   registry->RegisterStringPref(prefs::kContentSuggestionsSubscriptionDataToken,
                                std::string());
 }
 }  // namespace ntp_snippets