Implement SharedMemory::NewAnonymousReadOnly(contents).

base/memory/shared_memory_win.cc

Index: base/memory/shared_memory_win.cc
diff --git a/base/memory/shared_memory_win.cc b/base/memory/shared_memory_win.cc
index d27ebc1d209b8d561b16edcca90ddf78d312e4e6..77741bc0d9d62184b231f724c23d9abd78d138a5 100644
--- a/base/memory/shared_memory_win.cc
+++ b/base/memory/shared_memory_win.cc
@@ -189,13 +189,14 @@ bool SharedMemory::Unmap() {
 
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle *new_handle,
-                                        bool close_self) {
+                                        bool close_self,
+                                        ShareMode share_mode) {
   *new_handle = 0;
   DWORD access = FILE_MAP_READ;
   DWORD options = 0;
   HANDLE mapped_file = mapped_file_;
   HANDLE result;
-  if (!read_only_)
+  if (share_mode == SHARE_CURRENT_MODE && !read_only_)
     access |= FILE_MAP_WRITE;
   if (close_self) {
     // DUPLICATE_CLOSE_SOURCE causes DuplicateHandle to close mapped_file.