Revert CL 117933003. Re-add resource speculative prefetching code.

chrome/browser/predictors/resource_prefetch_predictor_factory.cc

+// Copyright 2014 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/predictors/resource_prefetch_predictor_factory.h"
+
+#include "chrome/browser/history/history_service_factory.h"
+#include "chrome/browser/predictors/predictor_database_factory.h"
+#include "chrome/browser/predictors/resource_prefetch_common.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace predictors {
+
+// static
+ResourcePrefetchPredictor* ResourcePrefetchPredictorFactory::GetForProfile(
+    content::BrowserContext* context) {
+  return static_cast<ResourcePrefetchPredictor*>(
+      GetInstance()->GetServiceForBrowserContext(context, true));
+}
+
+// static
+ResourcePrefetchPredictorFactory*
+ResourcePrefetchPredictorFactory::GetInstance() {
+  return Singleton<ResourcePrefetchPredictorFactory>::get();
+}
+
+ResourcePrefetchPredictorFactory::ResourcePrefetchPredictorFactory()
+    : BrowserContextKeyedServiceFactory(
+        "ResourcePrefetchPredictor",
+        BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(HistoryServiceFactory::GetInstance());
+  DependsOn(PredictorDatabaseFactory::GetInstance());
+}
+
+ResourcePrefetchPredictorFactory::~ResourcePrefetchPredictorFactory() {}
+
+KeyedService*
+    ResourcePrefetchPredictorFactory::BuildServiceInstanceFor(
+        content::BrowserContext* context) const {
+  Profile* profile = Profile::FromBrowserContext(context);
+
+  ResourcePrefetchPredictorConfig config;
+  if (!IsSpeculativeResourcePrefetchingEnabled(profile, &config))
+    return NULL;
+
+  return new ResourcePrefetchPredictor(config, profile);
+}
+
+}  // namespace predictors