Pass file Regions along with FDs to child processes on Android

base/files/memory_mapped_file.cc

Index: base/files/memory_mapped_file.cc
diff --git a/base/files/memory_mapped_file.cc b/base/files/memory_mapped_file.cc
index 891fcffc4cb434b74729657b7981a400729f2e61..45015b7aa34b49e8dc087c8e612f2d290bdda54b 100644
--- a/base/files/memory_mapped_file.cc
+++ b/base/files/memory_mapped_file.cc
@@ -16,10 +16,11 @@ const MemoryMappedFile::Region MemoryMappedFile::Region::kWholeFile(
 MemoryMappedFile::Region::Region(base::LinkerInitialized) : offset(0), size(0) {
 }
 
+MemoryMappedFile::Region::Region() : offset(-1), size(-1) {
+}
+
 MemoryMappedFile::Region::Region(int64 offset, int64 size)
     : offset(offset), size(size) {
-  DCHECK_GE(offset, 0);
-  DCHECK_GT(size, 0);
 }
 
 bool MemoryMappedFile::Region::operator==(
@@ -59,6 +60,11 @@ bool MemoryMappedFile::Initialize(File file, const Region& region) {
   if (IsValid())
     return false;
 
+  if (!(region == Region::kWholeFile)) {

[Lei Zhang, 2015/06/02 18:59:11]

should we implement operator!= ?

[agrieve, 2015/06/02 19:21:38]

Seems reasonable doesn't it? :) Done!

+    DCHECK_GE(region.offset, 0);
+    DCHECK_GT(region.size, 0);
+  }
+
   file_ = file.Pass();
 
   if (!MapFileRegionToMemory(region)) {