Revert 200603 "Make Windows traversal checking handle pathologic..."

Seems to have broken base_unittests on Linux ASAN.

> Make Windows traversal checking handle pathological cases 
> 
> Different versions of Windows have undocumented quirks in handling path components 
> (e.g. truncating or ignoring certain leading or trailing characters). In order to avoid potential 
> security bugs we're going to treat components more loosely and risk a few unlikely false 
> positives from FilePath::ReferencesParent(). 
> 
> BUG=181617
> R=brettw@chromium.org, ericu@chromium.org
> 
> Review URL: https://codereview.chromium.org/12771015

TBR=jschuh@chromium.org

Review URL: https://codereview.chromium.org/15095015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@200610 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 08c627d0b9f2854baf1e2b37229b7101b2b21a53
diff --git a/base/files/file_path.cc b/base/files/file_path.cc
index 03ccbcd..e9495a1 100644
--- a/base/files/file_path.cc
+++ b/base/files/file_path.cc
@@ -553,15 +553,8 @@
   std::vector<StringType>::const_iterator it = components.begin();
   for (; it != components.end(); ++it) {
     const StringType& component = *it;
-    // Windows has odd, undocumented behavior with path components containing
-    // only whitespace and . characters. So, if all we see is . and
-    // whitespace, then we treat any .. sequence as referencing parent.
-    // For simplicity we enforce this on all platforms.
-    if (component.find_first_not_of(FILE_PATH_LITERAL(". \n\r\t")) ==
-            std::string::npos &&
-        component.find(kParentDirectory) != std::string::npos) {
+    if (component == kParentDirectory)
       return true;
-    }
   }
   return false;
 }