DevTools: promisify ContentProvider.requestContent and all its clients.

third_party/WebKit/Source/devtools/front_end/bindings/ResourceScriptMapping.js

 /*
  * Copyright (C) 2012 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 404 matching lines @@
     },
 
     /**
      * @return {boolean}
      */
     isMergingToVM: function()
     {
         return this._isMergingToVM;
     },
 
+    /**
+     * @return {!Promise}
+     */
     checkMapping: function()
     {
         if (!this._script)
-            return;
+            return Promise.resolve();
         if (typeof this._scriptSource !== "undefined")
-            return;
-        this._script.requestContent(callback.bind(this));
+            return Promise.resolve();
+        return this._script.requestContent().then(callback.bind(this));
 
         /**
          * @param {?string} source
          * @this {WebInspector.ResourceScriptFile}
          */
         function callback(source)
         {
             this._scriptSource = source;
             this._update();
         }
@@ skipping 28 matching lines @@
     /**
      * @return {boolean}
      */
     hasSourceMapURL: function()
     {
         return this._script && !!this._script.sourceMapURL;
     },
 
     __proto__: WebInspector.Object.prototype
 }