Remove command line/field trial support and configs for Isolate Extensions.

extensions/common/switches.h

 // Copyright 2013 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.
 
 #ifndef EXTENSIONS_COMMON_SWITCHES_H_
 #define EXTENSIONS_COMMON_SWITCHES_H_
 
 // All switches in alphabetical order. The switches should be documented
 // alongside the definition of their values in the .cc file.
 namespace extensions {
 
 namespace switches {
 
 extern const char kAllowHTTPBackgroundPage[];
 extern const char kAllowLegacyExtensionManifests[];
 extern const char kDisableDesktopCaptureAudio[];
 extern const char kDisableTabForDesktopShare[];
 extern const char kEmbeddedExtensionOptions[];
 extern const char kEnableEmbeddedExtensionOptions[];
 extern const char kEnableExperimentalExtensionApis[];
 extern const char kEnableOverrideBookmarksUI[];
 extern const char kEnableBLEAdvertising[];
 extern const char kErrorConsole[];
 extern const char kExtensionProcess[];
 extern const char kExtensionsOnChromeURLs[];
 extern const char kForceDevModeHighlighting[];
-extern const char kIsolateExtensions[];
 extern const char kLoadApps[];
 extern const char kScriptsRequireAction[];
 extern const char kEnableScriptsRequireAction[];
 #if defined(CHROMIUM_BUILD)
 extern const char kPromptForExternalExtensions[];
 #endif
 extern const char kShowComponentExtensionOptions[];
 extern const char kTraceAppSource[];
 extern const char kNativeCrxBindings[];
 extern const char kWhitelistedExtensionID[];
 extern const char kEnableCrxHashCheck[];
 extern const char kYieldBetweenContentScriptRuns[];
 
 }  // namespace switches
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_SWITCHES_H_