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

chrome/browser/devtools/chrome_devtools_discovery_provider.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_
 #define CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_
 
 #include "base/macros.h"
+#include "chrome/browser/ui/browser_tab_strip_tracker.h"
+#include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
 #include "components/devtools_discovery/devtools_discovery_manager.h"
 
 class ChromeDevToolsDiscoveryProvider :
-    public devtools_discovery::DevToolsDiscoveryManager::Provider {
+    public devtools_discovery::DevToolsDiscoveryManager::Provider,
+    public TabStripModelObserver {
  public:
   // Installs provider to devtools_discovery.
   static void Install();
 
   ~ChromeDevToolsDiscoveryProvider() override;
 
   // devtools_discovery::DevToolsDiscoveryManager::Provider implementation.
   devtools_discovery::DevToolsTargetDescriptor::List GetDescriptors() override;
 
  private:
   ChromeDevToolsDiscoveryProvider();
 
+  // TabStripModelObserver overrides.
+  void TabInsertedAt(content::WebContents* contents,
+                     int index,
+                     bool foreground) override;
+
+  BrowserTabStripTracker browser_tab_strip_tracker_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeDevToolsDiscoveryProvider);
 };
 
 #endif  // CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_