ImageCapture: introduce image_capture Blob to allow move-only semantics

third_party/WebKit/LayoutTests/imagecapture/resources/mock-imagecapture.js

 "use strict";
 
 let mockImageCaptureReady = define(
   'mockImageCapture',
   ['media/mojo/interfaces/image_capture.mojom',
    'mojo/public/js/bindings',
    'mojo/public/js/connection',
    'content/public/renderer/service_registry',
   ], (imageCapture, bindings, connection, serviceRegistry) => {
 
@@ skipping 15 matching lines @@
     getCapabilities(source_id) {
       return Promise.resolve(this.capabilities_);
     }
 
     setOptions(source_id, settings) {
       this.settings_ = settings;
       return Promise.resolve({ success : true });
     }
 
     takePhoto(source_id) {
-      return Promise.resolve({ mime_type : 'image/cat',
-                               data : "(,,,)=(^.^)=(,,,)" });
+      return Promise.resolve({ blob : { mime_type : 'image/cat',
+                                        data : new Array(2) } });
     }
 
     capabilities() {
       return this.capabilities_.capabilities;
     }
 
     options() {
       return this.settings_;
     }
 
   }
   return new MockImageCapture();
 });