Add --auto-open-devtools-for-tabs flag.

chrome/browser/devtools/BUILD.gn

 # Copyright 2014 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.
 
 if (!is_android) {
   import("//build/config/features.gni")
   import("//tools/grit/grit_rule.gni")
 }
 
 action("devtools_protocol_constants") {
@@ skipping 89 matching lines @@
       "device/tcp_device_provider.cc",
       "device/tcp_device_provider.h",
       "device/usb/android_rsa.cc",
       "device/usb/android_rsa.h",
       "device/usb/android_usb_device.cc",
       "device/usb/android_usb_device.h",
       "device/usb/android_usb_socket.cc",
       "device/usb/android_usb_socket.h",
       "device/usb/usb_device_provider.cc",
       "device/usb/usb_device_provider.h",
+      "devtools_auto_opener.cc",
+      "devtools_auto_opener.h",
       "devtools_contents_resizing_strategy.cc",
       "devtools_contents_resizing_strategy.h",
       "devtools_embedder_message_dispatcher.cc",
       "devtools_embedder_message_dispatcher.h",
       "devtools_file_helper.cc",
       "devtools_file_helper.h",
       "devtools_file_system_indexer.cc",
       "devtools_file_system_indexer.h",
       "devtools_file_watcher.cc",
       "devtools_file_watcher.h",
@@ skipping 13 matching lines @@
       "remote_debugging_server.h",
     ]
     if (enable_service_discovery) {
       sources += [
         "device/cast_device_provider.cc",
         "device/cast_device_provider.h",
       ]
     }
   }
 }