Show service worker navigation preload requests in DevTools Network tab.

Demo: https://youtu.be/I-Qe_Y-xYxE

Navigation Preload requests are initiated from the browser process.
This is different from the normal network requests which are initiated from the
renderer process.

When the DevTools show the normal requests in the Network tab, DevTool's
Network events (requestWillBeSent, responseReceived, loadingFinished etc) are
dispatched via InspectorInstrumentation and InspectorNetworkAgent.

This CL introduces new DevTool's Network events (navigationPreloadSent,
navigationPreloadResponseReceived, navigationPreloadFailed,
navigationPreloadFinished) which are dispatched via InspectorInstrumentation and
InspectorNetworkAgent from ServiceWorkerContextClient.

In the normal requests case, we record the request sending timestamp when the
renderer process will send the request in InspectorNetworkAgent::
willSendRequestInternal(). But in the navigation preload case, we record the
timestamp in the browser process, and send it to the service worker's renderer
process using FetchEventPreloadHandle.

BUG=649558

Review-Url: https://codereview.chromium.org/2620463002
Cr-Commit-Position: refs/heads/master@{#445630}

front_end/network/NetworkDataGridNode.js

@@ -785,6 +785,12 @@ Network.NetworkRequestNode = class extends Network.NetworkNode {
         cell.request = request;
         break;
 
+      case SDK.NetworkRequest.InitiatorType.Preload:
+        cell.title = Common.UIString('Preload');
+        cell.classList.add('network-dim-cell');
+        cell.appendChild(createTextNode(Common.UIString('Preload')));
+        break;
+
       default:
         cell.title = Common.UIString('Other');
         cell.classList.add('network-dim-cell');

front_end/sdk/NetworkLog.js

@@ -145,6 +145,8 @@ SDK.NetworkLog = class extends SDK.SDKModel {
           scriptId = topFrame.scriptId;
           break;
         }
+      } else if (initiator.type === Protocol.Network.InitiatorType.Preload) {
+        type = SDK.NetworkRequest.InitiatorType.Preload;
       }
     }
 

front_end/sdk/NetworkRequest.js

@@ -1136,7 +1136,8 @@ SDK.NetworkRequest.InitiatorType = {
   Other: 'other',
   Parser: 'parser',
   Redirect: 'redirect',
-  Script: 'script'
+  Script: 'script',
+  Preload: 'preload'
 };
 
 /** @typedef {!{name: string, value: string}} */

front_end/sdk/SubTargetsManager.js

@@ -130,8 +130,15 @@ SDK.SubTargetsManager = class extends SDK.SDKModel {
    * @return {number}
    */
   _capabilitiesForType(type) {
-    if (type === 'worker')
-      return SDK.Target.Capability.JS | SDK.Target.Capability.Log;
+    if (type === 'worker') {
+      var capabilities = SDK.Target.Capability.JS | SDK.Target.Capability.Log;
+      var parentTargetInfo = this.targetInfo(this.target());
+      var mainIsServiceWorker =
+          !this.target().parentTarget() && this.target().hasTargetCapability() && !this.target().hasJSCapability();
+      if ((parentTargetInfo && parentTargetInfo.type === 'service_worker') || mainIsServiceWorker)
+        capabilities |= SDK.Target.Capability.Network;
+      return capabilities;
+    }
     if (type === 'service_worker')
       return SDK.Target.Capability.Log | SDK.Target.Capability.Network | SDK.Target.Capability.Target;
     if (type === 'iframe') {
@@ -163,7 +170,7 @@ SDK.SubTargetsManager = class extends SDK.SDKModel {
 
     // Only pause new worker if debugging SW - we are going through the pause on start checkbox.
     var mainIsServiceWorker =
-        !this.target().parentTarget() && this.target().hasTargetCapability() && !this.target().hasBrowserCapability();
+        !this.target().parentTarget() && this.target().hasTargetCapability() && !this.target().hasJSCapability();
     if (mainIsServiceWorker && waitingForDebugger)
       target.debuggerAgent().pause();
     target.runtimeAgent().runIfWaitingForDebugger();