HeadlessWebContents Observers for devtools clients attaching/detatching

headless/lib/headless_devtools_client_browsertest.cc

 // Copyright 2016 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.
 
 #include <memory>
 
 #include "base/json/json_reader.h"
 #include "base/run_loop.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
@@ skipping 1004 matching lines @@
     EXPECT_TRUE(web_contents_->GetFrameTreeNodeIdForDevToolsAgentHostId(
         devtools_agent_host_id, &frame_tree_node_id));
     EXPECT_NE(0, frame_tree_node_id);
     FinishAsynchronousTest();
     return true;
   }
 };
 
 HEADLESS_ASYNC_DEVTOOLED_TEST_F(RawDevtoolsProtocolTest);
 
+class DevToolsAttachAndDetachNotifications
+    : public HeadlessAsyncDevTooledBrowserTest {
+ public:
+  void DevToolsClientAttached() override { dev_tools_client_attached_ = true; }
+
+  void RunDevTooledTest() override {
+    EXPECT_TRUE(dev_tools_client_attached_);
+    FinishAsynchronousTest();
+  }
+
+  void DevToolsClientDetached() override { dev_tools_client_detached_ = true; }
+
+  void TearDownOnMainThread() override {
+    EXPECT_TRUE(dev_tools_client_detached_);
+  }
+
+ private:
+  bool dev_tools_client_attached_ = false;
+  bool dev_tools_client_detached_ = false;
+};
+
+HEADLESS_ASYNC_DEVTOOLED_TEST_F(DevToolsAttachAndDetachNotifications);
+
 }  // namespace headless