Bug 1543151 - Implement DOM.getContentQuads. r=remote-protocol-reviewers,ato

Differential Revision: https://phabricator.services.mozilla.com/D27519

--HG--
extra : moz-landing-system : lando

remote/domains/content/DOM.jsm

@@ -8,4 +8,52 @@ var EXPORTED_SYMBOLS = ["DOM"];
 
 const {ContentProcessDomain} = ChromeUtils.import("chrome://remote/content/domains/ContentProcessDomain.jsm");
 
-class DOM extends ContentProcessDomain {}
+class DOM extends ContentProcessDomain {
+  constructor(session) {
+    super(session);
+    this.enabled = false;
+  }
+
+  destructor() {
+    this.disable();
+  }
+
+  // commands
+
+  async enable() {
+    if (!this.enabled) {
+      this.enabled = true;
+    }
+  }
+
+  disable() {
+    if (this.enabled) {
+      this.enabled = false;
+    }
+  }
+
+  getContentQuads({ objectId }) {
+    const Runtime = this.session.domains.get("Runtime");
+    if (!Runtime) {
+      throw new Error("Runtime domain is not instantiated");
+    }
+    const obj = Runtime.getRemoteObject(objectId);
+    if (!obj) {
+      throw new Error("Cannot find object with id = " + objectId);
+    }
+    const unsafeObject = obj.unsafeDereference();
+    if (!unsafeObject.getBoxQuads) {
+      throw new Error("RemoteObject is not a node");
+    }
+    let quads = unsafeObject.getBoxQuads({ relativeTo: this.content.document });
+    quads = quads.map(quad => {
+      return [
+        quad.p1.x, quad.p1.y,
+        quad.p2.x, quad.p2.y,
+        quad.p3.x, quad.p3.y,
+        quad.p4.x, quad.p4.y,
+      ].map(Math.round);
+    });
+    return { quads };
+  }
+}