[Android] Simplify "network predictions" preference to a boolean value.

chrome/browser/net/prediction_options.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/net/prediction_options.h"
 
 #include "base/logging.h"
 #include "chrome/browser/profiles/profile_io_data.h"
 #include "chrome/common/pref_names.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/network_change_notifier.h"
 
 namespace chrome_browser_net {
 
 namespace {
 
 // Since looking up preferences and current network connection are presumably
 // both cheap, we do not cache them here.
 NetworkPredictionStatus CanPrefetchAndPrerender(
     int network_prediction_options) {
   switch (network_prediction_options) {
     case NETWORK_PREDICTION_ALWAYS:
-      break;
-    case NETWORK_PREDICTION_NEVER:
-      return NetworkPredictionStatus::DISABLED_ALWAYS;
-    default:
-      DCHECK_EQ(NETWORK_PREDICTION_WIFI_ONLY, network_prediction_options);
+    case NETWORK_PREDICTION_WIFI_ONLY:
       if (net::NetworkChangeNotifier::IsConnectionCellular(
                  net::NetworkChangeNotifier::GetConnectionType())) {
         return NetworkPredictionStatus::DISABLED_DUE_TO_NETWORK;
+      } else {
+        return NetworkPredictionStatus::ENABLED;
       }
+    default:
+      DCHECK_EQ(NETWORK_PREDICTION_NEVER, network_prediction_options);
+      return NetworkPredictionStatus::DISABLED_ALWAYS;
   }
-  return NetworkPredictionStatus::ENABLED;
 }
 
 bool CanPreresolveAndPreconnect(int network_prediction_options) {
   // DNS preresolution and TCP preconnect are performed even on cellular
   // networks if the user setting is WIFI_ONLY.
   return network_prediction_options != NETWORK_PREDICTION_NEVER;
 }
 
 }  // namespace
 
@@ skipping 28 matching lines @@
 }
 
 bool CanPreresolveAndPreconnectUI(PrefService* prefs) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(prefs);
   return CanPreresolveAndPreconnect(
       prefs->GetInteger(prefs::kNetworkPredictionOptions));
 }
 
 }  // namespace chrome_browser_net