Add google-java-format to third_party.

Content of README.google

Name: Tool to reformat Java source code to comply with Google Java Style.
URL: https://github.com/google/google-java-format/releases/tag/google-java-format-1.7
Version: 1.7
Revision: NA
Date: September 17th 2019
License: See LICENSE
Change-Id: I4dee26d107ace9fced0ef6c7415c94ab3afef065
diff --git a/third_party/google-java-format.tar.gz.sha1 b/third_party/google-java-format.tar.gz.sha1
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index 0000000..a8e5af8
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+++ b/third_party/google-java-format.tar.gz.sha1
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+bcb8db97fd37fc84a0e8e67c4b5937740b6c3980
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