Adds a pref and a policy to decide if PDFs should always be opened externally.

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 311 matching lines @@
 extern const char kCurrentThemeTints[];
 extern const char kCurrentThemeDisplayProperties[];
 extern const char kExtensionsUIDeveloperMode[];
 extern const char kExtensionsUIDismissedADTPromo[];
 extern const char kExtensionCommands[];
 extern const char kPluginsLastInternalDirectory[];
 extern const char kPluginsPluginsList[];
 extern const char kPluginsDisabledPlugins[];
 extern const char kPluginsDisabledPluginsExceptions[];
 extern const char kPluginsEnabledPlugins[];
+extern const char kPluginsAlwaysOpenPdfExternally[];
 #if defined(ENABLE_PLUGINS)
 extern const char kPluginsShowDetails[];
 #endif
 extern const char kPluginsAllowOutdated[];
 extern const char kPluginsAlwaysAuthorize[];
 #if defined(ENABLE_PLUGIN_INSTALLATION)
 extern const char kPluginsMetadata[];
 extern const char kPluginsResourceCacheUpdate[];
 #endif
 extern const char kDefaultBrowserLastDeclined[];
@@ skipping 486 matching lines @@
 #endif
 
 extern const char kOriginTrialPublicKey[];
 extern const char kOriginTrialDisabledFeatures[];
 
 extern const char kComponentUpdatesEnabled[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_