[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js

Index: third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js
diff --git a/third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js b/third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js
index 98c55294a0bb0e25cd6304f6a8dfec1db6e2d391..a44d9bd8bfa01260a7001b7e25ff14b7449746ef 100644
--- a/third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js
+++ b/third_party/WebKit/Source/devtools/front_end/sdk/ServiceWorkerCacheModel.js
@@ -31,12 +31,14 @@ WebInspector.ServiceWorkerCacheModel.prototype = {
         if (this._enabled)
             return;
 
-        this.target().resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginAdded, this._securityOriginAdded, this);
-        this.target().resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginRemoved, this._securityOriginRemoved, this);
-
-        var securityOrigins = this.target().resourceTreeModel.securityOrigins();
-        for (var i = 0; i < securityOrigins.length; ++i)
-            this._addOrigin(securityOrigins[i]);
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this.target());
+        if (resourceTreeModel) {
+            resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginAdded, this._securityOriginAdded, this);
+            resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginRemoved, this._securityOriginRemoved, this);
+            var securityOrigins = resourceTreeModel.securityOrigins();
+            for (var i = 0; i < securityOrigins.length; ++i)
+                this._addOrigin(securityOrigins[i]);
+        }
         this._enabled = true;
     },
 
@@ -54,7 +56,8 @@ WebInspector.ServiceWorkerCacheModel.prototype = {
         for (var cache of this._caches.values())
             this._cacheRemoved(cache);
         this._caches.clear();
-        var securityOrigins = this.target().resourceTreeModel.securityOrigins();
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this.target());
+        var securityOrigins = resourceTreeModel ? resourceTreeModel.securityOrigins() : [];
         for (var securityOrigin of securityOrigins)
             this._loadCacheNames(securityOrigin);
     },
@@ -128,9 +131,10 @@ WebInspector.ServiceWorkerCacheModel.prototype = {
         for (var cache of this._caches.values())
             this._cacheRemoved(cache);
         this._caches.clear();
-        if (this._enabled) {
-            this.target().resourceTreeModel.removeEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginAdded, this._securityOriginAdded, this);
-            this.target().resourceTreeModel.removeEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginRemoved, this._securityOriginRemoved, this);
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(this.target());
+        if (this._enabled && resourceTreeModel) {
+            resourceTreeModel.removeEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginAdded, this._securityOriginAdded, this);
+            resourceTreeModel.removeEventListener(WebInspector.ResourceTreeModel.EventTypes.SecurityOriginRemoved, this._securityOriginRemoved, this);
         }
     },