Add initial support for runtime permissions in android M.

chrome/browser/content_settings/permission_infobar_delegate.cc

Index: chrome/browser/content_settings/permission_infobar_delegate.cc
diff --git a/chrome/browser/content_settings/permission_infobar_delegate.cc b/chrome/browser/content_settings/permission_infobar_delegate.cc
index 61178273803c180a36aaf1acb47d0581ce61ca69..847aa5ef06ea9f27917b38253b0d356ca406aa8f 100644
--- a/chrome/browser/content_settings/permission_infobar_delegate.cc
+++ b/chrome/browser/content_settings/permission_infobar_delegate.cc
@@ -50,6 +50,11 @@ bool PermissionInfobarDelegate::Cancel() {
   return true;
 }
 
+PermissionInfobarDelegate*
+PermissionInfobarDelegate::AsPermissionInfobarDelegate() {
+  return this;
+}
+
 void PermissionInfobarDelegate::SetPermission(bool update_content_setting,
                                               bool allowed) {
   action_taken_ = true;