On Windows, if intention for shared memory name is empty then we pass NULL.

With new appcontainer token in picture, it fails to create shared memory with empty name like "", it explicity seem to need NULL for anonymous.

BUG=455496
R=cpu

Review URL: https://codereview.chromium.org/950993003

Cr-Commit-Position: refs/heads/master@{#317689}

base/memory/shared_memory_win.cc

@@ -144,7 +144,8 @@ bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
                          rand_values[2], rand_values[3]);
   }
   mapped_file_ = CreateFileMapping(INVALID_HANDLE_VALUE, &sa,
-      PAGE_READWRITE, 0, static_cast<DWORD>(rounded_size), name_.c_str());
+      PAGE_READWRITE, 0, static_cast<DWORD>(rounded_size),
+      name_.empty() ? nullptr : name_.c_str());
   if (!mapped_file_)
     return false;