Remove NetPrefObserver class and two prefs that do not do anything.

chrome/common/pref_names.h

 // Copyright (c) 2012 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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 
 #include <stddef.h>
@@ skipping 151 matching lines @@
 #endif
 #if defined(OS_MACOSX)
 extern const char kConfirmToQuitEnabled[];
 extern const char kHideFullscreenToolbar[];
 extern const char kShowFullscreenToolbar[];
 #endif
 extern const char kPromptForDownload[];
 extern const char kAlternateErrorPagesEnabled[];
 extern const char kDnsPrefetchingStartupList[];
 extern const char kDnsPrefetchingHostReferralList[];
-extern const char kDisableSpdy[];
 extern const char kHttpServerProperties[];
 #if defined(OS_ANDROID)
 extern const char kLastPolicyCheckTime[];
 #endif
 extern const char kInstantUIZeroSuggestUrlPrefix[];
-extern const char kNetworkPredictionEnabled[];
 extern const char kNetworkPredictionOptions[];
 extern const char kDefaultAppsInstallState[];
 extern const char kHideWebStoreIcon[];
 #if defined(OS_CHROMEOS)
 extern const char kTapToClickEnabled[];
 extern const char kTapDraggingEnabled[];
 extern const char kEnableTouchpadThreeFingerClick[];
 extern const char kNaturalScroll[];
 extern const char kPrimaryMouseButtonRight[];
 extern const char kMouseSensitivity[];
@@ skipping 621 matching lines @@
 #endif  // defined(GOOGLE_CHROME_BUILD)
 extern const char kMediaRouterFirstRunFlowAcknowledged[];
 #endif
 
 extern const char kOriginTrialPublicKey[];
 extern const char kOriginTrialDisabledFeatures[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_