app_shell: Fix focus on opening new app windows

extensions/shell/browser/shell_app_delegate.h

Index: extensions/shell/browser/shell_app_delegate.h
diff --git a/extensions/shell/browser/shell_app_delegate.h b/extensions/shell/browser/shell_app_delegate.h
index ecf48485d79512356ef2013f28b4d3ed7256f433..8c9be2e83af985f75c7d06277e3133edecf9863d 100644
--- a/extensions/shell/browser/shell_app_delegate.h
+++ b/extensions/shell/browser/shell_app_delegate.h
@@ -6,11 +6,14 @@
 #define EXTENSIONS_SHELL_BROWSER_SHELL_APP_DELEGATE_H_
 
 #include "extensions/browser/app_window/app_delegate.h"
+#include "content/public/browser/web_contents_observer.h"
 
 namespace extensions {
 
-// app_shell's AppDelegate implementation.
-class ShellAppDelegate : public AppDelegate {
+// AppDelegate implementation for app_shell. Sets focus after the WebContents is
+// created. Ignores most operations that would create a new dialog or window.
+class ShellAppDelegate : public AppDelegate,
+                         public content::WebContentsObserver {
  public:
   ShellAppDelegate();
   ~ShellAppDelegate() override;
@@ -48,6 +51,9 @@ class ShellAppDelegate : public AppDelegate {
   bool IsWebContentsVisible(content::WebContents* web_contents) override;
   void SetTerminatingCallback(const base::Closure& callback) override;
 
+  // content::WebContentsObserver:
+  void RenderViewCreated(content::RenderViewHost* render_view_host) override;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(ShellAppDelegate);
 };