Add support for Page.getResourceTree

sky/framework/inspector/page-agent.sky

 <import src="/sky/framework/xmlhttprequest.sky" as="XMLHttpRequest" />
 <script>
 function Page(delegate) {
   this.delegate_ = delegate;
 }
 
 Page.prototype.enable = function() {
 };
 
 Page.prototype.canScreencast = function() {
@@ skipping 15 matching lines @@
       'content' : request.responseText,
     };
     this.delegate_.sendResponse(message_id, message);
   }.bind(this);
   request.open("GET", params.url);
   request.send();
 
   return this.delegate_.ASYNC_RESPONSE;
 };
 
+Page.prototype._treeOrderWalk = function(root, visit) {
+  // HTML defines tree-order as a pre-order depth-first walk.
+  var node = root;
+  var parent_stack = [];
+  // WTF? Why is !![] == true in this forsaken language?

[abarth-chromium, 2014/11/18 23:08:42]

Not sure we want this comment...

+  while (parent_stack.length || node) {
+    if (node) {
+      visit(node);
+      if (node.nextSibling)
+        parent_stack.push(node.nextSibling);
+      node = node.firstChild;
+    } else
+      node = parent_stack.pop();
+  }
+}
+
+Page.prototype._getElementsByTagName = function(root, tag_name) {
+  var elements = [];
+  this._treeOrderWalk(root, function(node) {
+    if (node.tagName == tag_name)
+      elements.push(node);
+  });
+  return elements;
+}
+
+// Javascript is possibly the worst language known to man.
+// ES6 has Array.from which theoretically does this.
+Page.prototype._arrayFromIterator = function(iterator) {
+  var a = [];
+  for (var e of iterator)
+    a.push(e);
+  return a;
+}
+
+Page.prototype._resourcesMapForSubtree = function(root_doc) {
+  var resource_map = new Map;
+  function _addResource(url, type, mimeType) {
+    var absolute_url = new URL(url, document.URL);
+    if (resource_map.has(absolute_url))
+      return;
+    resource_map.set(absolute_url, {
+      'url': String(absolute_url),
+      'type': type,
+      'mimeType': mimeType,
+    })
+  }
+
+  var pending_docs = [root_doc];
+  while (pending_docs.length) {
+    var doc = pending_docs.pop();
+    var imports = this._getElementsByTagName(doc, 'import');
+    imports.forEach(function(imp) {
+      // FIXME: It's no longer possible to walk into an import. :(
+      // pending_docs.push(imp.import);
+      _addResource(imp.getAttribute('src'), 'Document', 'text/html');
+    });
+    var images = this._getElementsByTagName(doc, 'img');
+    images.forEach(function(img) {
+      // FIXME: Can't determine the type of an image from the DOM.
+      _addResource(img.getAttribute('src'), 'Image', 'image/unknown');
+    });
+  }
+  return resource_map;
+}
+
 Page.prototype.getResourceTree = function() {
   // Unclear if this is all needed, but if we don't return something here
   // the inspector hits an exception in WebInspector.ResourceTreeModel.
+  var resources_iter = this._resourcesMapForSubtree(document).values();
   return {
     "frameTree": {
       "frame": {
         "id": "1",
         "loaderId": "1",
-        "url": document.URL,
+        "url": String(document.URL),
         "mimeType": "text/html",
-        "securityOrigin": document.URL,
+        "securityOrigin": String(document.URL),
       },
-      "resources": [], // FIXME
+      "resources": this._arrayFromIterator(resources_iter),
     }
   };
 };
 
 module.exports = Page;
 </script>