Merge commit for internal changes

diff --cc tensorflow/contrib/data/python/kernel_tests/BUILD
Simple merge

diff --cc tensorflow/contrib/lite/toco/toco_flags.proto
Simple merge

diff --cc tensorflow/core/debug/debug_io_utils.cc
Simple merge

diff --cc tensorflow/core/grappler/costs/graph_properties.cc
Simple merge

diff --cc tensorflow/core/kernels/conv_ops_gpu_3.cu.cc
Simple merge

diff --cc tensorflow/core/platform/cloud/gcs_file_system.cc
Simple merge

diff --cc tensorflow/python/estimator/estimator.py
Simple merge

diff --cc tensorflow/python/ops/math_ops.py
Simple merge

diff --cc tensorflow/tensorflow.bzl
Simple merge