Add component for feature engagement tracking.

chrome/browser/feature_engagement_tracker/feature_engagement_tracker_factory.cc

+// Copyright 2017 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/feature_engagement_tracker/feature_engagement_tracker_factory.h"
+
+#include "base/files/file_path.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/singleton.h"
+#include "base/sequenced_task_runner.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/chrome_constants.h"
+#include "components/feature_engagement_tracker/public/feature_engagement_tracker.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/browser/browser_thread.h"
+
+// static
+FeatureEngagementTrackerFactory*
+FeatureEngagementTrackerFactory::GetInstance() {
+  return base::Singleton<FeatureEngagementTrackerFactory>::get();
+}
+
+// static
+feature_engagement_tracker::FeatureEngagementTracker*
+FeatureEngagementTrackerFactory::GetForBrowserContext(
+    content::BrowserContext* context) {
+  return static_cast<feature_engagement_tracker::FeatureEngagementTracker*>(
+      GetInstance()->GetServiceForBrowserContext(context, true));
+}
+
+FeatureEngagementTrackerFactory::FeatureEngagementTrackerFactory()
+    : BrowserContextKeyedServiceFactory(
+          "feature_engagement_tracker::FeatureEngagementTracker",
+          BrowserContextDependencyManager::GetInstance()) {}
+
+FeatureEngagementTrackerFactory::~FeatureEngagementTrackerFactory() = default;
+
+KeyedService* FeatureEngagementTrackerFactory::BuildServiceInstanceFor(
+    content::BrowserContext* context) const {
+  Profile* profile = Profile::FromBrowserContext(context);
+
+  scoped_refptr<base::SequencedTaskRunner> background_task_runner =
+      content::BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
+          content::BrowserThread::GetBlockingPool()->GetSequenceToken());
+
+  base::FilePath storage_dir = profile->GetPath().Append(
+      chrome::kFeatureEngagementTrackerStorageDirname);
+
+  return feature_engagement_tracker::FeatureEngagementTracker::Create(
+      storage_dir, background_task_runner);
+}
+
+content::BrowserContext*
+FeatureEngagementTrackerFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  return context;

[David Trainor- moved to gerrit, 2017/03/29 18:00:03]

Do we want a separate one for on and off the record contexts?  It looks like
that's what this is doing.

[nyquist, 2017/03/30 22:58:54]

Redirecting incognito to main context for now.

+}