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

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

 {
     "version": { "major": "1", "minor": "2" },
     "domains": [{
         "domain": "Inspector",
         "experimental": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2981 matching lines @@
                     { "name": "startCharacterIndex", "type": "integer", "description": "The starting index in characters, for this post layout textbox substring." },
                     { "name": "numCharacters", "type": "integer", "description": "The number of characters in this post layout textbox substring." }
                 ],
                 "description": "Details of post layout rendered text positions. The exact layout should not be regarded as stable and may change between versions.",
                 "experimental": true
             },
             {
                 "id": "LayoutTreeNode",
                 "type": "object",
                 "properties": [
-                    { "name": "nodeId", "$ref": "DOM.NodeId", "description": "The id of the related DOM node matching one from DOM.GetDocument." },
+                    { "name": "nodeId", "$ref": "DOM.NodeId", "description": "The id of the related DOM node in the domNodes array returned by getDocumentSnapshot." },

[pfeldman, 2017/05/31 17:56:37]

It can't be of type NodeId - NodeId is a node handle type which it no longer is.
It is now the "index" in the domNodes array.

                     { "name": "boundingBox", "$ref": "DOM.Rect", "description": "The absolute position bounding box." },
                     { "name": "layoutText", "type": "string", "optional": true, "description": "Contents of the LayoutText if any" },
                     { "name": "inlineTextNodes", "type": "array", "optional": true, "items": { "$ref": "InlineTextBox" }, "description": "The post layout inline text nodes, if any." },
-                    { "name": "styleIndex", "type": "integer", "optional": true, "description": "Index into the computedStyles array returned by getLayoutTreeAndStyles." }
+                    { "name": "styleIndex", "type": "integer", "optional": true, "description": "Index into the computedStyles array returned by getDocumentSnapshot." }
                 ],
                 "description": "Details of an element in the DOM tree with a LayoutObject.",
                 "experimental": true
             },
             {
                 "id": "ComputedStyle",
                 "type": "object",
                 "properties": [
                     { "name": "properties", "type": "array", "items": { "$ref": "CSSComputedStyleProperty" } }
                 ],
@@ skipping 187 matching lines @@
                 "name": "getBackgroundColors",
                 "parameters": [
                     { "name": "nodeId", "$ref": "DOM.NodeId", "description": "Id of the node to get background colors for." }
                 ],
                 "returns": [
                     { "name": "backgroundColors", "type": "array", "items": { "type": "string" }, "description": "The range of background colors behind this element, if it contains any visible text. If no visible text is present, this will be undefined. In the case of a flat background color, this will consist of simply that color. In the case of a gradient, this will consist of each of the color stops. For anything more complicated, this will be an empty array. Images will be ignored (as if the image had failed to load).", "optional": true }
                 ],
                 "experimental": true
             },
             {
-                "name": "getLayoutTreeAndStyles",
+                "name": "getDocumentSnapshot",
                 "parameters": [
-                    { "name": "computedStyleWhitelist", "type": "array", "items": { "type": "string" }, "description": "Whitelist of computed styles to return." }
+                    { "name": "computedStyleWhitelist", "type": "array", "items": { "type": "string" }, "description": "Whitelist of computed styles to return." },
+                    { "name": "domDepth", "type": "integer", "optional": true, "description": "The maximum depth at which children should be retrieved, defaults to 1. Use -1 for the entire subtree or provide an integer larger than 0." },

[pfeldman, 2017/05/31 17:56:37]

it is called depth everywhere else.

+                    { "name": "pierce", "type": "boolean", "optional": true, "description": "Whether or not iframes and shadow roots should be traversed when returning the subtree (default is false)." }
                 ],
                 "returns": [
-                    { "name": "layoutTreeNodes", "type": "array", "items": { "$ref": "LayoutTreeNode" } },
-                    { "name": "computedStyles", "type": "array", "items": { "$ref": "ComputedStyle" } }
+                    { "name": "domNodes", "type": "array", "items": { "$ref": "DOM.Node" }, "description": "The nodes in the DOM tree. These nodes will also be considered as known to the DOM domain client in the future." },

[pfeldman, 2017/05/31 17:56:37]

I don't think it makes much sense - we should not combine the "inspection" and
"scripting/automation" semantics here. It is unlikely that the snapshot client
wants to receive all the node-related notifications post the snapshot retrieval
and you are forcing this.

+                    { "name": "layoutTreeNodes", "type": "array", "items": { "$ref": "LayoutTreeNode" }, "description": "The nodes in the layout tree." },
+                    { "name": "computedStyles", "type": "array", "items": { "$ref": "ComputedStyle" }, "description": "Whitelisted ComputedStyle properties for each node in the layout tree." }
                 ],
-                "description": "For the main document and any content documents, return the LayoutTreeNodes and a whitelisted subset of the computed style. It only returns pushed nodes, on way to pull all nodes is to call DOM.getDocument with a depth of -1.",
+                "description": "Returns a document snapshot, including the DOM tree of the root node up to the given depth in a flattened array, as well as layout and white-listed computed style information for the nodes. Requires that the DOM domain is enabled.",
                 "experimental": true
             },
             {
                 "name": "startRuleUsageTracking",
                 "description": "Enables the selector recording.",
                 "experimental": true
             },
             {
                 "name": "takeCoverageDelta",
                 "description": "Obtain list of rules that became used since last call to this method (or since start of coverage instrumentation)",
@@ skipping 1440 matching lines @@
                 "parameters": [
                     { "name": "windowId", "$ref": "WindowID", "description": "Browser window id." }
                 ],
                 "returns": [
                     { "name": "bounds", "$ref": "Bounds", "description": "Bounds information of the window. When window state is 'minimized', the restored window position and size are returned." }
                 ]
             }
         ]
     }]
 }