Add commands to manage tabs and contexts to Browser Domain

headless/lib/browser/headless_web_contents_impl.h

Index: headless/lib/browser/headless_web_contents_impl.h
diff --git a/headless/lib/browser/headless_web_contents_impl.h b/headless/lib/browser/headless_web_contents_impl.h
index e0eec04afa2f6e30115e2461c45b06620cdca072..dde41581d34b93bbc8b9ab99f9d1d69a3b5caf3e 100644
--- a/headless/lib/browser/headless_web_contents_impl.h
+++ b/headless/lib/browser/headless_web_contents_impl.h
@@ -35,6 +35,8 @@ class HeadlessWebContentsImpl : public HeadlessWebContents,
  public:
   ~HeadlessWebContentsImpl() override;
 
+  static HeadlessWebContentsImpl* From(HeadlessWebContents* web_contents);
+
   static std::unique_ptr<HeadlessWebContentsImpl> Create(
       HeadlessWebContents::Builder* builder,
       aura::Window* parent_window,
@@ -59,6 +61,8 @@ class HeadlessWebContentsImpl : public HeadlessWebContents,
 
   void Close() override;
 
+  std::string GetDevtoolsAgentHostId();
+
  private:
   // Takes ownership of |web_contents|.
   HeadlessWebContentsImpl(content::WebContents* web_contents,