base: Remove the string logging from CHECK().

ui/gfx/image/image.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/image/image.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 739 matching lines @@
 
 internal::ImageRep* Image::AddRepresentation(
     std::unique_ptr<internal::ImageRep> rep) const {
   CHECK(storage_.get());
   RepresentationType type = rep->type();
   auto result =
       storage_->representations().insert(std::make_pair(type, std::move(rep)));
 
   // insert should not fail (implies that there was already a representation of
   // that type in the map).
-  CHECK(result.second) << "type was already in map.";
+  // type was already in map.
+  CHECK(result.second);
 
   return result.first->second.get();
 }
 
 }  // namespace gfx