Change other usages of .size() to .empty() when applicable.

base/file_path.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 <algorithm>
 
 #include "base/file_path.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 231 matching lines @@
   return AppendRelativePath(child, NULL);
 }
 
 bool FilePath::AppendRelativePath(const FilePath& child,
                                   FilePath* path) const {
   std::vector<StringType> parent_components;
   std::vector<StringType> child_components;
   GetComponents(&parent_components);
   child.GetComponents(&child_components);
 
-  if (parent_components.size() >= child_components.size())
-    return false;
-  if (parent_components.empty())
+  if (parent_components.empty() ||
+      parent_components.size() >= child_components.size())
     return false;
 
   std::vector<StringType>::const_iterator parent_comp =
       parent_components.begin();
   std::vector<StringType>::const_iterator child_comp =
       child_components.begin();
 
 #if defined(FILE_PATH_USES_DRIVE_LETTERS)
   // Windows can access case sensitive filesystems, so component
   // comparisions must be case sensitive, but drive letters are
@@ skipping 942 matching lines @@
 
 #if defined(FILE_PATH_USES_WIN_SEPARATORS)
 FilePath FilePath::NormalizeWindowsPathSeparators() const {
   StringType copy = path_;
   for (size_t i = 1; i < arraysize(kSeparators); ++i) {
     std::replace(copy.begin(), copy.end(), kSeparators[i], kSeparators[0]);
   }
   return FilePath(copy);
 }
 #endif