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

net/disk_cache/blockfile/mapped_file_posix.cc

Index: net/disk_cache/blockfile/mapped_file_posix.cc
diff --git a/net/disk_cache/blockfile/mapped_file_posix.cc b/net/disk_cache/blockfile/mapped_file_posix.cc
index 99cf49c1890dfbd5d474460666aaa3bc420d170a..2eee9dceb8214715bb82c5a017e8ef83be58b4c7 100644
--- a/net/disk_cache/blockfile/mapped_file_posix.cc
+++ b/net/disk_cache/blockfile/mapped_file_posix.cc
@@ -19,8 +19,11 @@ void* MappedFile::Init(const base::FilePath& name, size_t size) {
     return NULL;
 
   size_t temp_len = size ? size : 4096;
-  if (!size)
+  if (!size) {
     size = GetLength();
+    if (!size)
+      return NULL;

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

same same

+  }
 
   buffer_ = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED,
                  platform_file(), 0);