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

net/base/file_stream.h

 // Copyright (c) 2008 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.
 
 // This file defines FileStream, a basic interface for reading and writing files
 // synchronously or asynchronously with support for seeking to an offset.
 // Note that even when used asynchronously, only one operation is supported at
 // a time.
 
 #ifndef NET_BASE_FILE_STREAM_H_
@@ skipping 25 matching lines @@
   // opened.
   FileStream(base::PlatformFile file, int flags);
 
   ~FileStream();
 
   // Call this method to close the FileStream.  It is OK to call Close
   // multiple times.  Redundant calls are ignored.
   // Note that if there are any pending async operations, they'll be aborted.
   void Close();
 
+  // Release performs the same actions as Close, but doesn't actually close the
+  // underlying PlatformFile.
+  void Release();
+
   // Call this method to open the FileStream.  The remaining methods
   // cannot be used unless this method returns OK.  If the file cannot be
   // opened then an error code is returned.
   // open_flags is a bitfield of base::PlatformFileFlags
   int Open(const FilePath& path, int open_flags);
 
-  // Returns true if Open succeeded and Close has not been called.
+  // Calling this method is functionally the same as constructing the object
+  // with the non-default constructor. This method can only be used if the
+  // FileSteam isn't currently open (i.e. was constructed with the default
+  // constructor).
+  int Open(base::PlatformFile file, int open_flags);
+
+  // Returns true if Open succeeded and neither Close nor Release have been
+  // called.
   bool IsOpen() const;
 
   // Adjust the position from where data is read.  Upon success, the stream
   // position relative to the start of the file is returned.  Otherwise, an
   // error code is returned.  It is not valid to call Seek while a Read call
   // has a pending completion.
   int64 Seek(Whence whence, int64 offset);
 
   // Returns the number of bytes available to read from the current stream
   // position until the end of the file.  Otherwise, an error code is returned.
@@ skipping 65 matching lines @@
 
   base::PlatformFile file_;
   int open_flags_;
 
   DISALLOW_COPY_AND_ASSIGN(FileStream);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_FILE_STREAM_H_