base: Remove the string logging from CHECK().

chrome/browser/chromeos/login/mixin_based_browser_test.cc

Index: chrome/browser/chromeos/login/mixin_based_browser_test.cc
diff --git a/chrome/browser/chromeos/login/mixin_based_browser_test.cc b/chrome/browser/chromeos/login/mixin_based_browser_test.cc
index 765f8ab5a2989b0dfb8b08720936fd83f15fcb47..8af6889cbac20b8315b2eab3d61a94eae88c0452 100644
--- a/chrome/browser/chromeos/login/mixin_based_browser_test.cc
+++ b/chrome/browser/chromeos/login/mixin_based_browser_test.cc
@@ -57,8 +57,8 @@ void MixinBasedBrowserTest::TearDownInProcessBrowserTestFixture() {
 }
 
 void MixinBasedBrowserTest::AddMixin(MixinBasedBrowserTest::Mixin* mixin) {
-  CHECK(!setup_was_launched_)
-      << "You are trying to add a mixin after setting up has already started.";
+  // You are trying to add a mixin after setting up has already started.
+  CHECK(!setup_was_launched_);
   mixins_.push_back(mixin);
 }