Put Filter into namespace net.

net/base/filter_unittest.cc

Index: net/base/filter_unittest.cc
diff --git a/net/base/filter_unittest.cc b/net/base/filter_unittest.cc
index 9c20d699944bb9b92ca4859ecb2f0c4f5d92055b..3bf7c94eb66a28cbf6c3abfc3e9339169f5dd28e 100644
--- a/net/base/filter_unittest.cc
+++ b/net/base/filter_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -6,6 +6,8 @@
 #include "net/base/mock_filter_context.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+namespace net {
+
 class FilterTest : public testing::Test {
 };
 
@@ -344,3 +346,5 @@ TEST(FilterTest, SupportedMimeGzip) {
   Filter::FixupEncodingTypes(filter_context, &encoding_types);
   EXPECT_TRUE(encoding_types.empty());
 }
+
+}  // namespace net