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

headless/public/util/flat_dom_tree_extractor.h

-// 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.
-
-#ifndef HEADLESS_PUBLIC_UTIL_DOM_TREE_EXTRACTOR_H_
-#define HEADLESS_PUBLIC_UTIL_DOM_TREE_EXTRACTOR_H_
-
-#include <unordered_map>
-#include <vector>
-
-#include "base/macros.h"
-#include "headless/public/devtools/domains/css.h"
-#include "headless/public/devtools/domains/dom.h"
-#include "headless/public/headless_export.h"
-
-namespace headless {
-class HeadlessDevToolsClient;
-
-// A utility class for extracting information from the DOM via DevTools. In
-// addition, it also extracts details of bounding boxes and layout text (NB the
-// exact layout should not be regarded as stable, it's subject to change without
-// notice).
-class HEADLESS_EXPORT FlatDomTreeExtractor {
- public:
-  explicit FlatDomTreeExtractor(HeadlessDevToolsClient* devtools_client);
-  ~FlatDomTreeExtractor();
-
-  using NodeId = int;
-  using Index = size_t;
-
-  class HEADLESS_EXPORT DomTree {
-   public:
-    DomTree();
-    DomTree(DomTree&& other);
-    ~DomTree();
-
-    // Flattened dom tree. The root node is always the first entry.
-    std::vector<const dom::Node*> dom_nodes_;
-
-    // Map of node IDs to indexes into |dom_nodes_|.
-    std::unordered_map<NodeId, Index> node_id_to_index_;
-
-    std::vector<const css::LayoutTreeNode*> layout_tree_nodes_;
-
-    std::vector<const css::ComputedStyle*> computed_styles_;
-
-   private:
-    friend class FlatDomTreeExtractor;
-
-    // Owns the raw pointers in |dom_nodes_|.
-    std::unique_ptr<dom::GetFlattenedDocumentResult> document_result_;
-
-    // Owns the raw pointers in |layout_tree_nodes_|.
-    std::unique_ptr<css::GetLayoutTreeAndStylesResult>
-        layout_tree_and_styles_result_;
-
-    DISALLOW_COPY_AND_ASSIGN(DomTree);
-  };
-
-  using DomResultCB = base::Callback<void(DomTree)>;
-
-  // Extracts all nodes from the DOM.  This is an asynchronous operation and
-  // it's an error to call ExtractDom while a previous operation is in flight.
-  void ExtractDomTree(const std::vector<std::string>& css_style_whitelist,
-                      DomResultCB callback);
-
- private:
-  void OnDocumentFetched(
-      std::unique_ptr<dom::GetFlattenedDocumentResult> result);
-
-  void OnLayoutTreeAndStylesFetched(
-      std::unique_ptr<css::GetLayoutTreeAndStylesResult> result);
-
-  void MaybeExtractDomTree();
-  void EnumerateNodes(const dom::Node* node);
-  void ExtractLayoutTreeNodes();
-  void ExtractComputedStyles();
-
-  DomResultCB callback_;
-  DomTree dom_tree_;
-  bool work_in_progress_;
-  HeadlessDevToolsClient* devtools_client_;  // NOT OWNED
-  base::WeakPtrFactory<FlatDomTreeExtractor> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(FlatDomTreeExtractor);
-};
-
-}  // namespace headless
-
-#endif  // HEADLESS_PUBLIC_UTIL_DOM_TREE_EXTRACTOR_H_