[Extensions] Clean up the handling of ExtensionHostMsg_Request

extensions/shell/browser/shell_extensions_browser_client.cc

Index: extensions/shell/browser/shell_extensions_browser_client.cc
diff --git a/extensions/shell/browser/shell_extensions_browser_client.cc b/extensions/shell/browser/shell_extensions_browser_client.cc
index 01a7e75beeed441f3722f178a4787b2cb4bcfc11..a79d86630c3ce49a6537ea81d30253ff002534bf 100644
--- a/extensions/shell/browser/shell_extensions_browser_client.cc
+++ b/extensions/shell/browser/shell_extensions_browser_client.cc
@@ -19,6 +19,7 @@
 #include "extensions/shell/browser/api/generated_api_registration.h"
 #include "extensions/shell/browser/shell_extension_host_delegate.h"
 #include "extensions/shell/browser/shell_extension_system_factory.h"
+#include "extensions/shell/browser/shell_extension_web_contents_observer.h"
 #include "extensions/shell/browser/shell_extensions_api_client.h"
 #include "extensions/shell/browser/shell_runtime_api_delegate.h"
 
@@ -240,4 +241,10 @@ void ShellExtensionsBrowserClient::SetAPIClientForTest(
   api_client_.reset(api_client);
 }
 
+ExtensionWebContentsObserver*
+ShellExtensionsBrowserClient::GetExtensionWebContentsObserver(
+    content::WebContents* web_contents) {
+  return ShellExtensionWebContentsObserver::FromWebContents(web_contents);
+}
+
 }  // namespace extensions