[devtools] Allow resolving node objects by backend id.

DOMSnapshot domain users (primarily automation users) don't receive
nodeIds, only backendNodeIds. Still, they'd like to interact with
node objects via JS.

Bug: 546953
Change-Id: Idbce383d9b264038b737bc316620fd308e839510
Reviewed-on: https://chromium-review.googlesource.com/559390
Commit-Queue: Eric Seckler <eseckler@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485242}

third_party/WebKit/LayoutTests/inspector-protocol/dom/dom-resolveNode-expected.txt

+Tests that DOM.resolveNode accepts a nodeId or backendNodeId.
+description: #document
+description: #document
+

third_party/WebKit/LayoutTests/inspector-protocol/dom/dom-resolveNode.js

+(async function(testRunner) {
+  var {page, session, dp} = await testRunner.startHTML(
+    '', 'Tests that DOM.resolveNode accepts a nodeId or backendNodeId.');
+
+  dp.DOM.enable();
+  var response = await dp.DOM.getDocument({depth: 0});
+  if (!response.result)
+    testRunner.log(JSON.stringify(response));
+  var nodeId = response.result.root.nodeId;
+  var backendNodeId = response.result.root.backendNodeId;
+
+  response = await dp.DOM.resolveNode({nodeId: nodeId});
+  if (!response.result || !response.result.object.description)
+    testRunner.log(JSON.stringify(response));
+  testRunner.log("description: " + response.result.object.description);
+
+  response = await dp.DOM.resolveNode({backendNodeId: backendNodeId});
+  if (!response.result || !response.result.object.description)
+    testRunner.log(JSON.stringify(response));
+  testRunner.log("description: " + response.result.object.description);
+
+  testRunner.completeTest();
+})

third_party/WebKit/Source/core/inspector/InspectorDOMAgent.cpp

@@ -1283,12 +1283,22 @@ Response InspectorDOMAgent::getNodeForLocation(
 }
 
 Response InspectorDOMAgent::resolveNode(
-    int node_id,
+    protocol::Maybe<int> node_id,
+    protocol::Maybe<int> backend_node_id,
     Maybe<String> object_group,
     std::unique_ptr<v8_inspector::protocol::Runtime::API::RemoteObject>*
         result) {
   String object_group_name = object_group.fromMaybe("");
-  Node* node = NodeForId(node_id);
+  Node* node = nullptr;
+
+  if (node_id.isJust() == backend_node_id.isJust())
+    return Response::Error("Either nodeId or backendNodeId must be specified.");
+
+  if (node_id.isJust())
+    node = NodeForId(node_id.fromJust());
+  else
+    node = DOMNodeIds::NodeForId(backend_node_id.fromJust());
+
   if (!node)
     return Response::Error("No node with given id found");
   *result = ResolveNode(node, object_group_name);

third_party/WebKit/Source/core/inspector/InspectorDOMAgent.h

@@ -153,7 +153,8 @@ class CORE_EXPORT InspectorDOMAgent final
       std::unique_ptr<protocol::Array<int>>* node_ids) override;
   protocol::Response setInspectedNode(int node_id) override;
   protocol::Response resolveNode(
-      int node_id,
+      protocol::Maybe<int> node_id,
+      protocol::Maybe<int> backend_node_id,
       protocol::Maybe<String> object_group,
       std::unique_ptr<v8_inspector::protocol::Runtime::API::RemoteObject>*)
       override;

third_party/WebKit/Source/core/inspector/browser_protocol.json

@@ -2637,13 +2637,14 @@
             {
                 "name": "resolveNode",
                 "parameters": [
-                    { "name": "nodeId", "$ref": "NodeId", "description": "Id of the node to resolve." },
+                    { "name": "nodeId", "$ref": "NodeId", "optional": true, "description": "Id of the node to resolve." },
+                    { "name": "backendNodeId", "$ref": "DOM.BackendNodeId", "optional": true, "description": "Backend identifier of the node to resolve." },
                     { "name": "objectGroup", "type": "string", "optional": true, "description": "Symbolic group name that can be used to release multiple objects." }
                 ],
                 "returns": [
                     { "name": "object", "$ref": "Runtime.RemoteObject", "description": "JavaScript object wrapper for given node." }
                 ],
-                "description": "Resolves JavaScript node object for given node id."
+                "description": "Resolves the JavaScript node object for a given NodeId or BackendNodeId."
             },
             {
                 "name": "getAttributes",

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

@@ -866,7 +866,7 @@ SDK.DOMNode = class {
    * @return {!Promise<?SDK.RemoteObject>}
    */
   async resolveToObject(objectGroup) {
-    var object = await this._agent.resolveNode(this.id, objectGroup);
+    var object = await this._agent.resolveNode(this.id, undefined, objectGroup);
     return object && this._domModel._runtimeModel.createRemoteObject(object);
   }