CHECK that shared bitmap was mapped on POSIX.

content/child/child_shared_bitmap_manager.cc

Index: content/child/child_shared_bitmap_manager.cc
diff --git a/content/child/child_shared_bitmap_manager.cc b/content/child/child_shared_bitmap_manager.cc
index 3b1800d2e21786838af041cab64e0f327f2d73b7..904dc45ed0f0b5e857143b0d8e6efcdf8866d200 100644
--- a/content/child/child_shared_bitmap_manager.cc
+++ b/content/child/child_shared_bitmap_manager.cc
@@ -34,7 +34,7 @@ scoped_ptr<cc::SharedBitmap> ChildSharedBitmapManager::AllocateSharedBitmap(
   sender_->Send(new ChildProcessHostMsg_SyncAllocateSharedBitmap(
       memory_size, id, &handle));
   memory = make_scoped_ptr(new base::SharedMemory(handle, false));
-  memory->Map(memory_size);
+  CHECK(memory->Map(memory_size));
 #else
   memory.reset(ChildThread::AllocateSharedMemory(memory_size, sender_));
   CHECK(memory);