[Android] Handle null values in BuildInfo.
[Android] Handle null values in BuildInfo.

In some emulator environments, BuildInfo constants can be null.

BUG=601081

Review URL: https://codereview.chromium.org/1866023002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#385509}

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