[PIP] Add picture in picture flag and switch.

chrome/common/chrome_switches.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.
 
 // Defines the shared command-line switches used by code in the Chrome
 // directory that don't have anywhere more specific to go.
 
 #ifndef CHROME_COMMON_CHROME_SWITCHES_H_
 #define CHROME_COMMON_CHROME_SWITCHES_H_
 
@@ skipping 105 matching lines @@
 extern const char kEnableExtensionActivityLogTesting[];
 extern const char kEnableFastUnload[];
 extern const char kEnableMaterialDesignFeedback[];
 extern const char kEnableMaterialDesignPolicyPage[];
 extern const char kEnableNaCl[];
 extern const char kEnableNavigationTracing[];
 extern const char kEnableNetBenchmarking[];
 extern const char kEnableOfflineAutoReload[];
 extern const char kEnableOfflineAutoReloadVisibleOnly[];
 extern const char kEnablePermissionActionReporting[];
+extern const char kEnablePictureInPicture[];
 extern const char kEnablePotentiallyAnnoyingSecurityFeatures[];
 extern const char kEnablePowerOverlay[];
 extern const char kEnablePrintPreviewRegisterPromos[];
 extern const char kEnableProfiling[];
 extern const char kEnablePushApiBackgroundMode[];
 extern const char kEnableQuic[];
 extern const char kEnableSettingsWindow[];
 extern const char kEnableSiteEngagementEvictionPolicy[];
 extern const char kEnableSiteSettings[];
 extern const char kEnableSupervisedUserManagedBookmarksFolder[];
@@ skipping 235 matching lines @@
 #if defined(OS_WIN)
 bool GDITextPrintingEnabled();
 #endif
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace switches
 
 #endif  // CHROME_COMMON_CHROME_SWITCHES_H_