Support for cros touchpad 3-finger click as middle button.

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_
 #pragma once
 
@@ skipping 146 matching lines @@
 extern const char kInstantEnabled[];
 extern const char kInstantEnabledOnce[];
 extern const char kMultipleProfilePrefMigration[];
 extern const char kNetworkPredictionEnabled[];
 extern const char kDefaultAppsInstallState[];
 #if defined(OS_CHROMEOS)
 extern const char kAudioMute[];
 extern const char kAudioVolumeDb[];
 extern const char kAudioVolumePercent[];
 extern const char kTapToClickEnabled[];
+extern const char kEnableTouchpadThreeFingerClick[];
 extern const char kNaturalScroll[];
 extern const char kPrimaryMouseButtonRight[];
 extern const char kMouseSensitivity[];
 extern const char kTouchpadSensitivity[];
 extern const char kUse24HourClock[];
 extern const char kDisableGData[];
 extern const char kDisableGDataOverCellular[];
 extern const char kDisableGDataHostedFiles[];
 // TODO(yusukes): Change "kLanguageABC" to "kABC". The current form is too long
 // to remember and confusing. The prefs are actually for input methods and i18n
@@ skipping 511 matching lines @@
 extern const char kPointsBufferedForVelocity[];
 extern const char kRailBreakProportion[];
 extern const char kRailStartProportion[];
 #endif
 
 extern const char kInManagedMode[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_