Update from https://crrev.com/308331

base/memory/shared_memory_unittest.cc

 // Copyright (c) 2012 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/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/process/kill.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 242 matching lines @@
   }
 
   memory1.Close();
   memory2.Close();
 
   rv = memory1.Delete(test_name);
   EXPECT_TRUE(rv);
 }
 #endif
 
+// Check that memory is still mapped after its closed.
+TEST(SharedMemoryTest, CloseNoUnmap) {
+  const size_t kDataSize = 4096;
+
+  SharedMemory memory;
+  ASSERT_TRUE(memory.CreateAndMapAnonymous(kDataSize));
+  char* ptr = static_cast<char*>(memory.memory());
+  ASSERT_NE(ptr, static_cast<void*>(NULL));
+  memset(ptr, 'G', kDataSize);
+
+  memory.Close();
+
+  EXPECT_EQ(ptr, memory.memory());
+  EXPECT_EQ(SharedMemory::NULLHandle(), memory.handle());
+
+  for (size_t i = 0; i < kDataSize; i++) {
+    EXPECT_EQ('G', ptr[i]);
+  }
+
+  memory.Unmap();
+  EXPECT_EQ(nullptr, memory.memory());
+}
+
 // Create a set of N threads to each open a shared memory segment and write to
 // it. Verify that they are always reading/writing consistent data.
 TEST(SharedMemoryTest, MultipleThreads) {
   MultipleThreadMain::CleanUp();
   // On POSIX we have a problem when 2 threads try to create the shmem
   // (a file) at exactly the same time, since create both creates the
   // file and zerofills it.  We solve the problem for this unit test
   // (make it not flaky) by starting with 1 thread, then
   // intentionally don't clean up its shmem before running with
   // kNumThreads.
@@ skipping 418 matching lines @@
   SharedMemoryProcessTest::CleanUp();
 }
 
 MULTIPROCESS_TEST_MAIN(SharedMemoryTestMain) {
   return SharedMemoryProcessTest::TaskTestMain();
 }
 
 #endif  // !OS_IOS
 
 }  // namespace base