Always collect disk stats for rootfs.

[Random-Liu]

Always collect disk stats for root.

Kubelet needs it for all runtimes.

@dashpole Can you help me double check whether this is sufficient for CRI runtimes?

Based on my understanding and testing, this seems sufficient.

Signed-off-by: Lantao Liu lantaol@google.com

[Random-Liu]

/test pull-cadvisor-e2e

[dashpole]

container/common/container_hints_test.go:30:3: Errorf format %s has arg cHints of wrong type github.com/google/cadvisor/container/common.containerHints
container/common/container_hints_test.go:47:4: Errorf format %s has arg cHints of wrong type github.com/google/cadvisor/container/common.containerHints

I think maybe we updated the go version or something recently. Can you fix the go lint errors?

Your change looks correct, and should work for CRI runtimes.

[Random-Liu]

Fixed the test.

[dashpole]

lgtm