Headless: Remove obsolete Mojo code and some other obsolete APIs

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 993 matching lines @@
   }
 
   bool OnProtocolMessage(const std::string& devtools_agent_host_id,
                          const std::string& json_message,
                          const base::DictionaryValue& parsed_message) override {
     EXPECT_EQ(
         "{\"id\":1,\"result\":{\"result\":{\"type\":\"number\","
         "\"value\":2,\"description\":\"2\"}}}",
         json_message);
 
-    int frame_tree_node_id = 0;
-    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:
@@ skipping 11 matching lines @@
   }
 
  private:
   bool dev_tools_client_attached_ = false;
   bool dev_tools_client_detached_ = false;
 };
 
 HEADLESS_ASYNC_DEVTOOLED_TEST_F(DevToolsAttachAndDetachNotifications);
 
 }  // namespace headless