Add support for returning traces as streams in DevTools protocol

LayoutTests/http/tests/inspector-protocol/tracing-test.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var evalCallbackCallId = 3;
 
 initialize_tracingHarness = function()
 {
 
 InspectorTest.startTracing = function(callback)
@@ skipping 25 matching lines @@
 
     function tracingComplete(event)
     {
         InspectorTest.log("Tracing complete");
         InspectorTest.eventHandler["Tracing.tracingComplete"] = null;
         InspectorTest.eventHandler["Tracing.dataCollected"] = null;
         callback(InspectorTest.devtoolsEvents);
     }
 }
 
+InspectorTest.stopTracingAndSaveAsStream = function(callback)
+{
+    InspectorTest.eventHandler["Tracing.tracingComplete"] = tracingComplete;
+    InspectorTest.eventHandler["Tracing.dataCollected"] = dataCollected;
+    InspectorTest.sendCommand("Tracing.end", { returnAsStream: true });
+
+    function dataCollected(reply)
+    {
+        InspectorTest.log("FAIL: dataCollected event should not be fired when returning trace as stream.");
+
+    }
+
+    function tracingComplete(event)
+    {
+        InspectorTest.log("Tracing complete");
+        InspectorTest.eventHandler["Tracing.tracingComplete"] = null;
+        InspectorTest.eventHandler["Tracing.dataCollected"] = null;
+        callback(event.params.streamId);
+    }
+}
+
+InspectorTest.retrieveStream = function(streamId, offset, chunkSize, callback)
+{
+    var result = "";
+    var had_eof = false;
+
+    var readArguments = { id: streamId };
+    if (typeof chunkSize === "number")
+        readArguments.size = chunkSize;
+    var firstReadArguments = JSON.parse(JSON.stringify(readArguments));
+    if (typeof offset === "number")
+        firstReadArguments.offset = 0;
+    InspectorTest.sendCommandOrDie("IO.read", firstReadArguments, onChunkRead);
+    // Assure multiple in-lfight reads are fine (also, save on latencies).
+    InspectorTest.sendCommandOrDie("IO.read", readArguments, onChunkRead);
+
+    function onChunkRead(response)
+    {
+        if (had_eof)
+            return;
+        result += response.data;
+        if (response.eof) {
+            // Ignore stray callbacks from proactive read requests.
+            had_eof = true;
+            callback(result);
+            return;
+        }
+        InspectorTest.sendCommandOrDie("IO.read", readArguments, onChunkRead);
+    }
+}
+
 InspectorTest.findEvent = function(name, ph, condition)
 {
     for (var i = 0; i < InspectorTest.devtoolsEvents.length; i++) {
         var e = InspectorTest.devtoolsEvents[i];
         if (e.name === name && e.ph === ph && (!condition || condition(e)))
             return e;
     }
     throw new Error("Couldn't find event " + name + " / " + ph + "\n\n in " + JSON.stringify(InspectorTest.devtoolsEvents, null, 2));
 }
 
@@ skipping 36 matching lines @@
 
     if (!callback) {
         InspectorTest.addResult("Missing callback for async eval " + callId + ", perhaps callback invoked twice?");
         return;
     }
     delete InspectorTest._pendingEvalRequests[callId];
     callback(value);
 }
 
 }
-