Enable Device Discovery by default on Linux, ChromeOS and Windows.

chrome/browser/ui/webui/local_discovery/local_discovery_ui_browsertest.cc

 // 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.
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 124 matching lines @@
                    base::Unretained(&condition_devices_listed_))));
 
     ui_factory_.reset(new FakeLocalDiscoveryUIFactory(
         fake_lister.Pass()));
 
     AddLibrary(base::FilePath(FILE_PATH_LITERAL("local_discovery_ui_test.js")));
   }
 
   virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
     WebUIBrowserTest::SetUpCommandLine(command_line);
-    command_line->AppendSwitch(switches::kEnableDeviceDiscovery);
   }
 
   FakeLocalDiscoveryUIFactory* ui_factory() { return ui_factory_.get(); }
   TestMessageLoopCondition& condition_devices_listed() {
     return condition_devices_listed_;
   }
 
  private:
   scoped_ptr<FakeLocalDiscoveryUIFactory> ui_factory_;
   TestMessageLoopCondition condition_devices_listed_;
@@ skipping 25 matching lines @@
 
   ui_factory()->privet_lister()->delegate()->DeviceRemoved(
       kSampleServiceName);
 
   EXPECT_TRUE(WebUIBrowserTest::RunJavascriptTest("checkNoDevices"));
 }
 
 }  // namespace
 
 }  // namespace local_discovery