Add support for returning traces as streams in DevTools protocol

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

Index: LayoutTests/http/tests/inspector-protocol/tracing-test.js
diff --git a/LayoutTests/http/tests/inspector-protocol/tracing-test.js b/LayoutTests/http/tests/inspector-protocol/tracing-test.js
index c814263d5aecc227a3f1a0c76fd0e5daa5803ae3..afe431621c4b1accc37aefc6b13d482d038106e0 100644
--- a/LayoutTests/http/tests/inspector-protocol/tracing-test.js
+++ b/LayoutTests/http/tests/inspector-protocol/tracing-test.js
@@ -43,6 +43,57 @@ InspectorTest.stopTracing = function(callback)
     }
 }
 
+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++) {
@@ -99,4 +150,3 @@ InspectorTest.didInvokePageFunctionAsync = function(callId, value)
 }
 
 }
-