Implementing recent pages snapshot capture.

components/offline_pages/snapshot_controller.cc

 // 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/snapshot_controller.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/time/time.h"
@@ skipping 13 matching lines @@
     SnapshotController::Client* client)
     : task_runner_(task_runner),
       client_(client),
       state_(State::kReady),
       weak_ptr_factory_(this) {
 }
 
 SnapshotController::~SnapshotController() {}
 
 void SnapshotController::Reset() {
+  // Cancel potentially delayed tasks that relate to the previous 'session'.
+  weak_ptr_factory_.InvalidateWeakPtrs();
   state_ = State::kReady;
 }
 
 void SnapshotController::Stop() {
   state_ = State::kStopped;
 }
 
 void SnapshotController::PendingSnapshotCompleted() {
   // Unless the controller is "stopped", enable the subsequent snapshots.
   // Stopped state prevents any further snapshots form being started.
@@ skipping 16 matching lines @@
 void SnapshotController::DocumentOnLoadCompletedInMainFrame() {
   MaybeStartSnapshot();
   // No more snapshots after onLoad (there still can be other events
   // or delayed tasks that can try to start another snapshot)
   Stop();
 }
 
 void SnapshotController::MaybeStartSnapshot() {
   if (state_ != State::kReady)
     return;
-  if (client_->StartSnapshot())
-    state_ = State::kSnapshotPending;
+  state_ = State::kSnapshotPending;
+  client_->StartSnapshot();
 }
 
 size_t SnapshotController::GetDelayAfterDocumentAvailableForTest() {
   return kDelayAfterDocumentAvailable;
 }
 
 
 }  // namespace offline_pages