DevTools: promisify ContentProvider.requestContent and all its clients.

third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html

Index: third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html b/third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html
index a990004b4d986fa66d1b98e62398f942cb9c1711..87a7777a8d13c625807bd94def2f959afeb2c7f1 100644
--- a/third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html
+++ b/third_party/WebKit/LayoutTests/http/tests/inspector/stylesheet-source-mapping.html
@@ -52,9 +52,9 @@ function test()
         const documentURL = "http://localhost:8000/inspector/stylesheet-source-mapping.html";
         const frame = InspectorTest.resourceTreeModel.mainFrame;
         var resource = new WebInspector.Resource(target, null, url, documentURL, frame.id, frame.loaderId, WebInspector.resourceTypes.Stylesheet, mimeType);
-        resource.requestContent = function(callback)
+        resource.requestContent = function()
         {
-            callback(content, false, mimeType);
+            return Promise.resolve(content);
         }
         return resource;
     }
@@ -94,7 +94,7 @@ function test()
         InspectorTest.checkUILocation(scssUISourceCode, 4, 11, rawLocationToUILocation(4, 11));
         InspectorTest.checkUILocation(scssUISourceCode, 4, 13, rawLocationToUILocation(4, 15));
         InspectorTest.checkUILocation(scssUISourceCode, 4, 17, rawLocationToUILocation(4, 20));
-        scssUISourceCode.requestContent(didRequestContent);
+        scssUISourceCode.requestContent().then(didRequestContent);
 
         function didRequestContent(content, contentEncoded, mimeType)
         {