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

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index 5db2db73669565bc34ca2bebcc58d1bc7e395996..c8ecd930d8b07a1aff5320832eb6ccf98dcc2ca8 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -1186,6 +1186,9 @@ void ChromeBrowserMainParts::PostProfileInit() {
 #endif  // BUILDFLAG(ANDROID_JAVA_UI)
 
   LaunchDevToolsHandlerIfNeeded(parsed_command_line());
+  if (parsed_command_line().HasSwitch(::switches::kAutoOpenDevToolsForTabs))
+    g_browser_process->CreateDevToolsAutoOpener();
+
   for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
     chrome_extra_parts_[i]->PostProfileInit();
 }