Handle MOJO_RESULT_BUSY result in URLResponseBodyConsumer

third_party/WebKit/LayoutTests/http/tests/inspector/network-test.js

 // This goes before everything else to keep console message line number invariant.
 var lastXHRIndex = 0;
 function xhrLoadedCallback()
 {
     // We need to make sure the console message text is unique so that we don't end up with repeat count update only.
     console.log("XHR loaded: " + (++lastXHRIndex));
 }
 
 function makeSimpleXHR(method, url, async, callback)
 {
@@ skipping 27 matching lines @@
 }
 
 function makeXHRForJSONArguments(jsonArgs)
 {
     var args = JSON.parse(jsonArgs);
     makeXHR(args.method, args.url, args.async, args.user, args.password, args.headers || [], args.withCredentials, args.payload, args.type, xhrLoadedCallback);
 }
 
 function makeFetch(url, requestInitializer)
 {
-    return fetch(url, requestInitializer).catch(e => e);
+    return fetch(url, requestInitializer).then(res => {
+        // Call text(). Otherwise the backpressure mechanism may block loading.
+        res.text();
+        return res;
+    }).catch(e => e);
 }
 
 var initialize_NetworkTest = function() {
 
 InspectorTest.preloadPanel("network");
 
 InspectorTest.recordNetwork = function()
 {
     UI.panels.network._networkLogView.setRecording(true);
 }
@@ skipping 77 matching lines @@
     version: "formatAsTypeName",
     wait: "formatAsTypeName",
     _transferSize: "formatAsTypeName",
     _error: "skip"
 };
 // addObject checks own properties only, so make a deep copy rather than use prototype.
 InspectorTest.HARPropertyFormattersWithSize = JSON.parse(JSON.stringify(InspectorTest.HARPropertyFormatters));
 InspectorTest.HARPropertyFormattersWithSize.size = "formatAsTypeName";
 
 };