Introduce ThreadTaskRunnerHandle::OverrideForTesting and TestMockTimeTaskRunner::ScopedContext.

chrome/browser/android/offline_pages/recent_tab_helper.cc

 // Copyright (c) 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 "chrome/browser/android/offline_pages/recent_tab_helper.h"
 
 #include <queue>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 26 matching lines @@
 class DefaultDelegate: public offline_pages::RecentTabHelper::Delegate {
  public:
   DefaultDelegate() : is_low_end_device_(base::SysInfo::IsLowEndDevice()) {}
 
   // offline_pages::RecentTabHelper::Delegate
   std::unique_ptr<offline_pages::OfflinePageArchiver> CreatePageArchiver(
       content::WebContents* web_contents) override {
     return base::MakeUnique<offline_pages::OfflinePageMHTMLArchiver>(
         web_contents);
   }
-  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() override {
-    return base::ThreadTaskRunnerHandle::Get();
-  }
   bool GetTabId(content::WebContents* web_contents, int* tab_id) override {
     return offline_pages::OfflinePageUtils::GetTabId(web_contents, tab_id);
   }
   bool IsLowEndDevice() override { return is_low_end_device_; }
 
  private:
   // Cached value of whether low end device.
   bool is_low_end_device_;
 };
 }  // namespace
@@ skipping 100 matching lines @@
 }
 
 // Initialize lazily. It needs TabAndroid for initialization, which is also a
 // TabHelper - so can't initialize in constructor because of uncertain order
 // of creation of TabHelpers.
 bool RecentTabHelper::EnsureInitialized() {
   if (snapshot_controller_)  // Initialized already.
     return snapshots_enabled_;
 
   snapshot_controller_.reset(
-      new SnapshotController(delegate_->GetTaskRunner(), this));
+      new SnapshotController(base::ThreadTaskRunnerHandle::Get(), this));
   snapshot_controller_->Stop();  // It is reset when navigation commits.
 
   int tab_id_number = 0;
   tab_id_.clear();
 
   if (delegate_->GetTabId(web_contents(), &tab_id_number))
     tab_id_ = base::IntToString(tab_id_number);
 
   // TODO(dimich): When we have BackgroundOffliner, avoid capturing prerenderer
   // WebContents with its origin as well.
@@ skipping 282 matching lines @@
 }
 
 void RecentTabHelper::CancelInFlightSnapshots() {
   weak_ptr_factory_.InvalidateWeakPtrs();
   downloads_ongoing_snapshot_info_.reset();
   downloads_latest_saved_snapshot_info_.reset();
   last_n_ongoing_snapshot_info_.reset();
 }
 
 }  // namespace offline_pages