Fix gfx::Range::ToString() to use the correct format specifier.

ui/gfx/range/range_unittest.cc

 // Copyright (c) 2011 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 <sstream>
+
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/range/range.h"
 #include "ui/gfx/range/range_f.h"
 
 namespace {
 
 template <typename T>
 class RangeTest : public testing::Test {
 };
 
@@ skipping 230 matching lines @@
   EXPECT_EQ(0U, range.end());
 
   range = range_f.Ceil();
   EXPECT_EQ(0U, range.start());
   EXPECT_EQ(0U, range.end());
 
   range = range_f.Round();
   EXPECT_EQ(0U, range.start());
   EXPECT_EQ(0U, range.end());
 }
+
+TEST(RangeTest, ToString) {
+  gfx::Range range(4, 7);
+  EXPECT_EQ("{4,7}", range.ToString());
+
+  range = gfx::Range::InvalidRange();
+  std::ostringstream expected;
+  expected << "{" << range.start() << "," << range.end() << "}";
+  EXPECT_EQ(expected.str(), range.ToString());
+}