Disallow calling Map on currently-mapped SharedMemory

base/memory/shared_memory_unittest.cc

Index: base/memory/shared_memory_unittest.cc
diff --git a/base/memory/shared_memory_unittest.cc b/base/memory/shared_memory_unittest.cc
index b8999f6f3c59832811c9e5924d82f1cece638b5b..f2a9e7480fc43c7fad8f7e5bed3e5f6d285c3e97 100644
--- a/base/memory/shared_memory_unittest.cc
+++ b/base/memory/shared_memory_unittest.cc
@@ -477,7 +477,6 @@ TEST(SharedMemoryTest, MapAt) {
 
   SharedMemory memory;
   ASSERT_TRUE(memory.CreateAndMapAnonymous(kDataSize));
-  ASSERT_TRUE(memory.Map(kDataSize));
   uint32* ptr = static_cast<uint32*>(memory.memory());
   ASSERT_NE(ptr, static_cast<void*>(NULL));
 
@@ -497,6 +496,19 @@ TEST(SharedMemoryTest, MapAt) {
   }
 }
 
+TEST(SharedMemoryTest, MapTwice) {
+  const uint32 kDataSize = 1024;
+  SharedMemory memory;
+  bool rv = memory.CreateAndMapAnonymous(kDataSize);
+  EXPECT_TRUE(rv);
+
+  void* old_address = memory.memory();
+
+  rv = memory.Map(kDataSize);
+  EXPECT_FALSE(rv);
+  EXPECT_EQ(old_address, memory.memory());
+}
+
 #if defined(OS_POSIX)
 // Create a shared memory object, mmap it, and mprotect it to PROT_EXEC.
 TEST(SharedMemoryTest, AnonymousExecutable) {