DevTools: Extract TargetManager into its own file

third_party/WebKit/Source/devtools/devtools.gypi

 #
 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #         * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #         * Redistributions in binary form must reproduce the above
@@ skipping 143 matching lines @@
             'front_end/sdk/PaintProfiler.js',
             'front_end/sdk/RemoteObject.js',
             'front_end/sdk/Resource.js',
             'front_end/sdk/ResourceTreeModel.js',
             'front_end/sdk/RuntimeModel.js',
             'front_end/sdk/Script.js',
             'front_end/sdk/ServiceWorkerCacheModel.js',
             'front_end/sdk/ServiceWorkerManager.js',
             'front_end/sdk/SourceMap.js',
             'front_end/sdk/Target.js',
+            'front_end/sdk/TargetManager.js',
             'front_end/sdk/TracingManager.js',
             'front_end/sdk/TracingModel.js',
             'front_end/sdk/WorkerManager.js',
         ],
         'devtools_workspace_js_files': [
             'front_end/workspace/FileManager.js',
             'front_end/workspace/FileSystemMapping.js',
             'front_end/workspace/IsolatedFileSystem.js',
             'front_end/workspace/IsolatedFileSystemManager.js',
             'front_end/workspace/SearchConfig.js',
@@ skipping 686 matching lines @@
             'front_end/Images/toolbarItemSelected.png',
             'front_end/Images/touchCursor.png',
             'front_end/Images/touchCursor_2x.png',
             'front_end/Images/updateServiceWorker.svg',
         ],
         'devtools_extension_api_files': [
             'front_end/extensions/ExtensionAPI.js',
         ],
     },
 }