Move all components/offline_pages/ files into component/offline_pages/core

components/offline_pages/snapshot_controller.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 COMPONENTS_OFFLINE_PAGES_SNAPSHOT_CONTROLLER_H_
-#define COMPONENTS_OFFLINE_PAGES_SNAPSHOT_CONTROLLER_H_
-
-#include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
-#include "base/single_thread_task_runner.h"
-
-namespace offline_pages {
-
-// Takes various signals and produces StartSnapshot calls following a specific
-// policy. Can request snapshots multiple times per 'session'. Session can be
-// ended and another one started by calling Reset().
-// Main invariants:
-// - It never starts overlapping snapshots, Client reports when previous
-//   snapshot is done.
-// - The currently worked on (pending) snapshot is always allowed to complete,
-//   the new attempts to start a snapshot are ignored until it does.
-// - Some signals prevent more snapshots to be taken.
-//   OnLoad is currently such signal.
-// - Once Reset() is called on the SnapshotController, the delayed tasks are
-//   reset so no StartSnapshot calls is made 'cross-session'.
-class SnapshotController {
- public:
-  enum class State {
-    READY,             // Listening to input, will start snapshot when needed.
-    SNAPSHOT_PENDING,  // Snapshot is in progress, don't start another.
-    STOPPED,           // Terminal state, no snapshots until reset.
-  };
-
-  // Client of the SnapshotController.
-  class  Client {
-   public:
-    // Invoked at a good moment to start a snapshot. May be invoked multiple
-    // times, but not in overlapping manner - waits until
-    // PreviousSnapshotCompleted() before the next StatrSnapshot().
-    // Client should overwrite the result of previous snapshot with the new one,
-    // it is assumed that later snapshots are better then previous.
-    virtual void StartSnapshot() = 0;
-
-   protected:
-    virtual ~Client() {}
-  };
-
-  SnapshotController(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
-      SnapshotController::Client* client);
-  SnapshotController(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
-      SnapshotController::Client* client,
-      size_t delay_after_document_available_ms,
-      size_t delay_after_document_on_load_completed_ms);
-  virtual ~SnapshotController();
-
-  // Resets the 'session', returning controller to initial state.
-  void Reset();
-
-  // Stops current session, no more Client::StartSnapshot calls will be
-  // invoked from the SnapshotController until current session is Reset().
-  // Called by Client, for example when it encounters an error loading the page.
-  void Stop();
-
-  // The way for Client to report that previously started snapshot is
-  // now completed (so the next one can be started).
-  void PendingSnapshotCompleted();
-
-  // Invoked from WebContentObserver::DocumentAvailableInMainFrame
-  void DocumentAvailableInMainFrame();
-
-  // Invoked from WebContentObserver::DocumentOnLoadCompletedInMainFrame
-  void DocumentOnLoadCompletedInMainFrame();
-
-  size_t GetDelayAfterDocumentAvailableForTest();
-  size_t GetDelayAfterDocumentOnLoadCompletedForTest();
-
- private:
-  void MaybeStartSnapshot();
-  void MaybeStartSnapshotThenStop();
-
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  // Client owns this class.
-  SnapshotController::Client* client_;
-  SnapshotController::State state_;
-  size_t delay_after_document_available_ms_;
-  size_t delay_after_document_on_load_completed_ms_;
-
-  base::WeakPtrFactory<SnapshotController> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(SnapshotController);
-};
-
-}  // namespace offline_pages
-
-#endif  // COMPONENTS_OFFLINE_PAGES_SNAPSHOT_CONTROLLER_H_