Fix accidental deletion

Change-Id: I211b4137081df34206eb2673a61ca6179fd0e4e9

python/pyarrow/array.pyx

@@ -38,6 +38,7 @@ import pyarrow.schema as schema
 
 def total_allocated_bytes():
     cdef MemoryPool* pool = pyarrow.get_memory_pool()
+    return pool.bytes_allocated()
 
 
 cdef class Array:

python/pyarrow/tests/test_array.py

@@ -19,6 +19,10 @@ import pyarrow
 import pyarrow.formatting as fmt
 
 
+def test_total_bytes_allocated():
+    assert pyarrow.total_allocated_bytes() == 0
+
+
 def test_repr_on_pre_init_array():
     arr = pyarrow.array.Array()
     assert len(repr(arr)) > 0