Deprecate GetDirectoryFromPath on non-Windows.

base/file_util_unittest.cc

 // Copyright (c) 2010 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 "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 293 matching lines @@
   {L"/foo/bar/", L"/foo/bar"},
   {L"/foo/bar//", L"/foo/bar"},
   {L"/foo/bar", L"/foo"},
   {L"/foo/bar./", L"/foo/bar."},
   {L"/", L"/"},
   {L".", L"."},
   {L"..", L"."},  // yes, ".." technically lives in "."
 #endif
 };
 
+#if defined(OS_WIN)
+// This function is deprecated, and only exists on Windows anymore.
 TEST_F(FileUtilTest, GetDirectoryFromPath) {
   for (unsigned int i = 0; i < arraysize(dir_cases); ++i) {
     const dir_case& dir = dir_cases[i];
     const std::wstring parent =
         file_util::GetDirectoryFromPath(dir.full_path);
     EXPECT_EQ(dir.directory, parent);
   }
 }
+#endif
 
 TEST_F(FileUtilTest, CountFilesCreatedAfter) {
   // Create old file (that we don't want to count)
   FilePath old_file_name = test_dir_.Append(FILE_PATH_LITERAL("Old File.txt"));
   CreateTextFile(old_file_name, L"Just call me Mr. Creakybits");
 
   // Age to perfection
 #if defined(OS_WIN)
   PlatformThread::Sleep(100);
 #elif defined(OS_POSIX)
@@ skipping 1075 matching lines @@
   // modification times with 2s resolution.
   ASSERT_TRUE(base::Time::FromString(L"Tue, 15 Nov 1994, 12:45:26 GMT",
               &modification_time));
   ASSERT_TRUE(file_util::SetLastModifiedTime(foobar, modification_time));
   file_util::FileInfo file_info;
   ASSERT_TRUE(file_util::GetFileInfo(foobar, &file_info));
   ASSERT_TRUE(file_info.last_modified == modification_time);
 }
 
 }  // namespace