chrome://snippets-internals page for debugging NTP snippets.

chrome/browser/ui/webui/snippets_internals_message_handler.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_SNIPPETS_INTERNALS_MESSAGE_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_SNIPPETS_INTERNALS_MESSAGE_HANDLER_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/scoped_observer.h"
+#include "components/ntp_snippets/ntp_snippets_service.h"
+#include "content/public/browser/web_ui_message_handler.h"
+
+namespace base {
+class ListValue;
+}  // namespace base
+
+// The implementation for the chrome://snippets-internals page.
+class SnippetsInternalsMessageHandler
+    : public content::WebUIMessageHandler,
+      public ntp_snippets::NTPSnippetsServiceObserver {
+ public:
+  SnippetsInternalsMessageHandler();
+  ~SnippetsInternalsMessageHandler() override;
+
+ private:
+  // content::WebUIMessageHandler:
+  void RegisterMessages() override;
+
+  // ntp_snippets::NTPSnippetsServiceObserver:
+  // Send everytime the service loads a new set of data.
+  void NTPSnippetsServiceLoaded() override;
+  // Send when the service is shutting down.
+  void NTPSnippetsServiceShutdown() override;
+
+  void HandleLoaded(const base::ListValue* args);
+  void HandleClear(const base::ListValue* args);
+  void HandleClearDiscarded(const base::ListValue* args);
+  void HandleDownload(const base::ListValue* args);
+
+  void SendInitialData(ntp_snippets::NTPSnippetsService* service);

[Marc Treib, 2016/04/15 09:00:30]

optional: You could either store the snippets service in a member, or make a
GetSnippetsService method that gets it from the factory. Then you wouldn't have
to pass it around everywhere. Up to you though, it's also okay as is.

[jkrcal, 2016/04/15 14:11:51]

Done. I store it in a member.

+  void SendSnippets(ntp_snippets::NTPSnippetsService* service);
+  void SendDiscardedSnippets(ntp_snippets::NTPSnippetsService* service);
+  void SendHosts(ntp_snippets::NTPSnippetsService* service);
+  void SendJson(const std::string& json);
+  void SendBoolean(const std::string& name, bool value);
+  void SendString(const std::string& name, const std::string& value);
+
+  // For making sure this object is not added twice as an observer.

[Marc Treib, 2016/04/15 09:00:30]

Not really - IMO it's mostly for the automatic unregistration. But this doesn't
really need a comment anyway :)

[jkrcal, 2016/04/15 14:11:51]

Done.

+  ScopedObserver<ntp_snippets::NTPSnippetsService,
+                 ntp_snippets::NTPSnippetsServiceObserver> observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(SnippetsInternalsMessageHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_SNIPPETS_INTERNALS_MESSAGE_HANDLER_H_