Fix the case where the browser livelocks if we cannot open a file.

base/file_util_win.cc

Index: base/file_util_win.cc
diff --git a/base/file_util_win.cc b/base/file_util_win.cc
index 9133e7b5296ba6b7244e6b30d761adfee3a9d0b4..9def1a5dfdcdc527a3ec973f67d7482dd37edf78 100644
--- a/base/file_util_win.cc
+++ b/base/file_util_win.cc
@@ -216,6 +216,19 @@ bool PathExists(const FilePath& path) {
   return (GetFileAttributes(path.value().c_str()) != INVALID_FILE_ATTRIBUTES);
 }
 
+bool PathIsReadable(const FilePath& path) {
+  HANDLE dir =
+      CreateFile(path.value().c_str(), FILE_READ_DATA,

[wtc, 2010/01/12 19:51:02]

I'm surprised that we have to test if a file is readable
by trying to open it for reading.  But I couldn't find a
suitable Win32 function for this purpose with a quick
search.

In NSPR we're using the CRT function _access:
http://msdn.microsoft.com/en-us/library/1w06ktdy(VS.80).aspx
Not sure if that's better than our solution here.

[agl, 2010/01/25 14:14:09]

Ah, _access looks good. I've switched to using that. Thanks.

+                 FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                 NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL);
+
+  if (dir == INVALID_HANDLE_VALUE)
+    return false;
+
+  CloseHandle(dir);
+  return true;
+}
+
 bool PathIsWritable(const FilePath& path) {
   HANDLE dir =
       CreateFile(path.value().c_str(), FILE_ADD_FILE,