Prevent unused-variable warnings in the CrOS build with gcc 4.6.

chrome/browser/chromeos/login/screen_locker_views.cc

Index: chrome/browser/chromeos/login/screen_locker_views.cc
diff --git a/chrome/browser/chromeos/login/screen_locker_views.cc b/chrome/browser/chromeos/login/screen_locker_views.cc
index ed5657d69c1bfea90046f6be1100b129ba3c5720..77272a36b4ba82358f41448372b54f1934e28ace 100644
--- a/chrome/browser/chromeos/login/screen_locker_views.cc
+++ b/chrome/browser/chromeos/login/screen_locker_views.cc
@@ -796,8 +796,7 @@ void ScreenLockerViews::ShowCaptchaAndErrorMessage(const GURL& captcha_url,
     captcha_view_->set_delegate(this);
   }
   // CaptchaView ownership is passed to grab_container_.
-  views::View* view = secondary_view_.release();
-  view = NULL;
+  ignore_result(secondary_view_.release());
   screen_lock_view_->SetVisible(false);
   grab_container_->SetScreenLockView(captcha_view_);
   background_container_->SetScreenLockView(captcha_view_);
@@ -842,8 +841,7 @@ void ScreenLockerViews::OnCaptchaEntered(const std::string& captcha) {
   // ScreenLockView ownership is passed to grab_container_.
   // Need to save return value here so that compile
   // doesn't fail with "unused result" warning.
-  views::View* view = secondary_view_.release();
-  view = NULL;
+  ignore_result(secondary_view_.release());
   captcha_view_->SetVisible(false);
   grab_container_->SetScreenLockView(screen_lock_view_);
   background_container_->SetScreenLockView(screen_lock_view_);