Convert //extensions/browser from scoped_ptr to std::unique_ptr

extensions/browser/app_window/app_window_contents.h

Index: extensions/browser/app_window/app_window_contents.h
diff --git a/extensions/browser/app_window/app_window_contents.h b/extensions/browser/app_window/app_window_contents.h
index 732197c391cad0d597b00f1d9d001a72a7767436..85b56c7d62f1df019bcdbc1159643ff405cd4f97 100644
--- a/extensions/browser/app_window/app_window_contents.h
+++ b/extensions/browser/app_window/app_window_contents.h
@@ -7,8 +7,9 @@
 
 #include <stdint.h>
 
+#include <memory>
+
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "extensions/browser/app_window/app_window.h"
 #include "url/gurl.h"
@@ -53,7 +54,7 @@ class AppWindowContentsImpl : public AppWindowContents,
 
   AppWindow* host_;  // This class is owned by |host_|
   GURL url_;
-  scoped_ptr<content::WebContents> web_contents_;
+  std::unique_ptr<content::WebContents> web_contents_;
   bool is_blocking_requests_;
   bool is_window_ready_;