Make VEA test support videos with different coded size and visible size

base/files/memory_mapped_file_posix.cc

 // Copyright 2013 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 "base/files/memory_mapped_file.h"
 
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
@@ skipping 42 matching lines @@
         static_cast<uint64>(region.size) > std::numeric_limits<size_t>::max()) {
       DLOG(ERROR) << "Region bounds are not valid for mmap";
       return false;
     }
 
     map_start = static_cast<off_t>(aligned_start);
     map_size = static_cast<size_t>(aligned_size);
     length_ = static_cast<size_t>(region.size);
   }
 
+  int flags = PROT_READ;

[rvargas (doing something else), 2014/08/27 18:24:25]

I'm sorry, but you are still trying to make this automagically without callers
being fully aware of what they are doing.

If a caller wants to create a mapped section with write access, MemoryMappedFile
should have a clear API to explicitly allow that behavior. Either an argument
somewhere should specify the desired access, or some new method should declare
that intent.

Note that passing a file with read/write access is not an indication that the
mapped memory should also have read/write access. If a caller passes a file with
read only access and asks MemoryMappedFile for write access, we should let the
OS reject the operation (there is no reliable way to go back to File::Flags from
a File)

+  if (file_.flags() & File::FLAG_WRITE ||
+      file_.flags() & File::FLAG_APPEND)
+    flags |= PROT_WRITE;
   data_ = static_cast<uint8*>(mmap(NULL,
                                    map_size,
-                                   PROT_READ,
+                                   flags,
                                    MAP_SHARED,
                                    file_.GetPlatformFile(),
                                    map_start));
   if (data_ == MAP_FAILED) {
     DPLOG(ERROR) << "mmap " << file_.GetPlatformFile();
     return false;
   }
 
   data_ += data_offset;
   return true;
 }
 
 void MemoryMappedFile::CloseHandles() {
   ThreadRestrictions::AssertIOAllowed();
 
   if (data_ != NULL)
     munmap(data_, length_);
   file_.Close();
 
   data_ = NULL;
   length_ = 0;
 }
 
 }  // namespace base