[devtools] Add DOMSnapshot domain for dom+layout+style snapshots.

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

Index: third_party/WebKit/Source/core/inspector/InspectorDOMSnapshotAgent.cpp
diff --git a/third_party/WebKit/Source/core/inspector/InspectorDOMSnapshotAgent.cpp b/third_party/WebKit/Source/core/inspector/InspectorDOMSnapshotAgent.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a934220e0368fd3d279da446185376fe00471d93
--- /dev/null
+++ b/third_party/WebKit/Source/core/inspector/InspectorDOMSnapshotAgent.cpp
@@ -0,0 +1,56 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/inspector/InspectorDOMSnapshotAgent.h"
+
+#include "core/dom/Document.h"
+
+namespace blink {
+
+using protocol::Maybe;
+using protocol::Response;
+
+InspectorDOMSnapshotAgent::InspectorDOMSnapshotAgent(
+    InspectorCSSAgent* css_agent,
+    InspectorDOMAgent* dom_agent)
+    : css_agent_(css_agent), dom_agent_(dom_agent) {}
+
+InspectorDOMSnapshotAgent::~InspectorDOMSnapshotAgent() {}
+
+Response InspectorDOMSnapshotAgent::getSnapshot(
+    std::unique_ptr<protocol::Array<String>> style_whitelist,
+    Maybe<int> dom_depth,
+    Maybe<bool> pierce,
+    std::unique_ptr<protocol::Array<protocol::DOM::Node>>* dom_nodes,
+    std::unique_ptr<protocol::Array<protocol::CSS::LayoutTreeNode>>*
+        layout_tree_nodes,
+    std::unique_ptr<protocol::Array<protocol::CSS::ComputedStyle>>*
+        computed_styles) {
+  if (!dom_agent_->Enabled())
+    return Response::Error("DOM agent hasn't been enabled");
+
+  Document* document = dom_agent_->GetDocument();
+  if (!document)
+    return Response::Error("Document is not available");
+
+  // Update layout tree first, so that it won't change between
+  // getFlattenedDocument and getLayoutTreeAndStyles.
+  document->UpdateStyleAndLayoutTree();
+
+  Response response = dom_agent_->getFlattenedDocument(
+      std::move(dom_depth), std::move(pierce), dom_nodes);
+  if (!response.isSuccess())
+    return response;
+
+  return css_agent_->getLayoutTreeAndStyles(std::move(style_whitelist),
+                                            layout_tree_nodes, computed_styles);
+}
+
+DEFINE_TRACE(InspectorDOMSnapshotAgent) {
+  visitor->Trace(css_agent_);
+  visitor->Trace(dom_agent_);
+  InspectorBaseAgent::Trace(visitor);
+}
+
+}  // namespace blink