Added SharedMemory::MapFrom.

base/shared_memory_win.cc

Index: base/shared_memory_win.cc
diff --git a/base/shared_memory_win.cc b/base/shared_memory_win.cc
index 877ccd76e3310370b0394f196cbb6bee9290c581..e29b87a4ed5d891dd0a613af071e71157624845d 100644
--- a/base/shared_memory_win.cc
+++ b/base/shared_memory_win.cc
@@ -5,6 +5,7 @@
 #include "base/shared_memory.h"
 
 #include "base/logging.h"
+#include "base/sys_info.h"
 #include "base/utf_string_conversions.h"
 
 namespace base {
@@ -134,15 +135,20 @@ bool SharedMemory::Open(const std::string& name, bool read_only) {
   return false;
 }
 
-bool SharedMemory::Map(size_t bytes) {
+bool SharedMemory::MapFrom(off_t offset, size_t bytes) {
   if (mapped_file_ == NULL)
     return false;
 
   if (bytes > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
+  DCHECK_EQ(0U, offset & (SysInfo::VMAllocationGranularity() - 1));

[Mark Mentovai, 2013/01/15 21:51:42]

Same.

[Vitaly Buka (NO REVIEWS), 2013/01/15 22:13:05]

So do you advise to remove DCHECK?

   memory_ = MapViewOfFile(mapped_file_,
-      read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS, 0, 0, bytes);
+                          read_only_ ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
+                          static_cast<uint64>(offset) >> 32,
+                          static_cast<DWORD>(offset),
+                          bytes);
+  int e = GetLastError();

[Mark Mentovai, 2013/01/15 21:51:42]

Unused.

[Vitaly Buka (NO REVIEWS), 2013/01/15 22:13:05]

Done.

   if (memory_ != NULL) {
     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
         (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));