HeadlessWebContents Observers for devtools clients attaching/detatching

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 1dd6c6d6eb6ef03b0bea48312551ea0d565cf575..e578e8aede79e69bde39ea96086563e463d7753d 100644
--- a/headless/lib/browser/headless_web_contents_impl.h
+++ b/headless/lib/browser/headless_web_contents_impl.h
@@ -10,6 +10,7 @@
 #include <string>
 #include <unordered_map>
 
+#include "content/public/browser/devtools_agent_host_observer.h"
 #include "content/public/browser/render_process_host_observer.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "headless/lib/browser/headless_window_tree_host.h"
@@ -35,6 +36,7 @@ class WebContentsObserverAdapter;
 class HEADLESS_EXPORT HeadlessWebContentsImpl
     : public HeadlessWebContents,
       public HeadlessDevToolsTarget,
+      public content::DevToolsAgentHostObserver,
       public content::RenderProcessHostObserver,
       public content::WebContentsObserver {
  public:
@@ -65,7 +67,13 @@ class HEADLESS_EXPORT HeadlessWebContentsImpl
   void DetachClient(HeadlessDevToolsClient* client) override;
   bool IsAttached() override;
 
-  // RenderProcessHostObserver implementation:
+  // content::DevToolsAgentHostObserver implementation:
+  void DevToolsAgentHostAttached(
+      content::DevToolsAgentHost* agent_host) override;
+  void DevToolsAgentHostDetached(
+      content::DevToolsAgentHost* agent_host) override;
+
+  // content::RenderProcessHostObserver implementation:
   void RenderProcessExited(content::RenderProcessHost* host,
                            base::TerminationStatus status,
                            int exit_code) override;