Fix error handling in POSIX version of the base::File::GetLength.

net/disk_cache/blockfile/mapped_file_avoid_mmap_posix.cc

 // Copyright (c) 2012 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 "net/disk_cache/blockfile/mapped_file.h"
 
 #include <stdlib.h>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 
 namespace disk_cache {
 
 void* MappedFile::Init(const base::FilePath& name, size_t size) {
   DCHECK(!init_);
   if (init_ || !File::Init(name))
     return NULL;
 
-  if (!size)
+  if (!size) {
     size = GetLength();
+    if (!size)
+      return NULL;

[danakj, 2016/11/29 01:48:01]

0 should be okay again for this CL

+  }
 
   buffer_ = malloc(size);
   snapshot_ = malloc(size);
   if (buffer_ && snapshot_ && Read(buffer_, size, 0)) {
     memcpy(snapshot_, buffer_, size);
   } else {
     free(buffer_);
     free(snapshot_);
     buffer_ = snapshot_ = 0;
   }
@@ skipping 23 matching lines @@
     return;
 
   if (buffer_ && snapshot_) {
     Flush();
   }
   free(buffer_);
   free(snapshot_);
 }
 
 }  // namespace disk_cache