[NTP Snippets] Refactor background scheduling for remote suggestions

chrome/browser/android/ntp/ntp_snippets_launcher.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_ANDROID_NTP_NTP_SNIPPETS_LAUNCHER_H_
 #define CHROME_BROWSER_ANDROID_NTP_NTP_SNIPPETS_LAUNCHER_H_
 
 #include "base/android/jni_android.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "base/time/time.h"
-#include "components/ntp_snippets/remote/ntp_snippets_scheduler.h"
+#include "components/ntp_snippets/remote/persistent_scheduler.h"
 
 // Android implementation of ntp_snippets::NTPSnippetsScheduler.
 // The NTPSnippetsLauncher singleton owns the Java SnippetsLauncher object, and
 // is used to schedule the fetching of snippets. Runs on the UI thread.
-class NTPSnippetsLauncher : public ntp_snippets::NTPSnippetsScheduler {
+class NTPSnippetsLauncher
+    : public ntp_snippets::PersistentScheduler {

[tschumann, 2016/12/15 14:12:11]

sorry for joining the naming discussion so late.
Will there be further implementations of the PersistentScheduler interface?

Would the soft schedules also happen through an implementation of this?
I think what we really have here is a PeriodicTask. IMO, we are still mixing up
the concepts a bit about what are signals that influence the fetch-scheduling
and what is part of the actual scheduler.

(see further comments on PersistentScheduler::Listener).

I also see that we need to make progress here and volunteer to help with further
renamings. But that would be a topic I'd quickly like to discuss first, and then
see what's the quickest way to get us there.

[jkrcal, 2016/12/19 09:40:24]

No, this is meant just for the OS-dependent scheduler for persistent periodic
tasks. Based on an offline discussion, kept as it is.

  public:
   static NTPSnippetsLauncher* Get();
 
   // ntp_snippets::NTPSnippetsScheduler implementation.
   bool Schedule(base::TimeDelta period_wifi,
                 base::TimeDelta period_fallback) override;
   bool Unschedule() override;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<NTPSnippetsLauncher>;
 
   // Constructor and destructor marked private to enforce singleton.
   NTPSnippetsLauncher();
   virtual ~NTPSnippetsLauncher();
 
   base::android::ScopedJavaGlobalRef<jobject> java_launcher_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsLauncher);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_NTP_NTP_SNIPPETS_LAUNCHER_H_