DevTools: Cache the original content on UISourceCode

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

 /*
  * 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 42 matching lines @@
    * @param {!Workspace.UISourceCode} uiSourceCode
    * @param {function(?string)} callback
    */
   requestFileContent(uiSourceCode, callback) {
     var contentProvider = this._contentProviders[uiSourceCode.url()];
     contentProvider.requestContent().then(callback);
   }
 
   /**
    * @override
+   * @param {!Workspace.UISourceCode} uiSourceCode
+   * @return {!Promise<?string>}
+   */
+  requestOriginalFileContent(uiSourceCode) {
+    var fulfill;
+    var promise = new Promise(x => fulfill = x);
+    this.requestFileContent(uiSourceCode, fulfill);
+    return promise;
+  }
+
+  /**
+   * @override
    * @return {boolean}
    */
   isServiceProject() {
     return this._isServiceProject;
   }
 
   /**
    * @override
    * @param {!Workspace.UISourceCode} uiSourceCode
    * @return {!Promise<?Workspace.UISourceCodeMetadata>}
    */
   requestMetadata(uiSourceCode) {
     return Promise.resolve(uiSourceCode[Bindings.ContentProviderBasedProject._metadata]);
   }
 
   /**
    * @override
    * @return {boolean}
    */
   canSetFileContent() {
     return false;
   }
 
   /**
    * @override
    * @param {!Workspace.UISourceCode} uiSourceCode
    * @param {string} newContent
-   * @param {function(?string)} callback
+   * @param {function()} callback
    */
   setFileContent(uiSourceCode, newContent, callback) {
-    callback(null);
+    callback();
   }
 
   /**
    * @override
    * @return {boolean}
    */
   canRename() {
     return false;
   }
 
@@ skipping 195 matching lines @@
     this.workspace().addProject(this);
   }
 
   dispose() {
     this._contentProviders = {};
     this.removeProject();
   }
 };
 
 Bindings.ContentProviderBasedProject._metadata = Symbol('ContentProviderBasedProject.Metadata');