Ensure no changes to the JSONSerializer or PrefHashCalculator ever end up producing different hashes for all existing Value::Type.

The current JSON serialization used "appears" to be standard and future-proof (i.e., doesn't use pretty_print or anything silly).

However, the hashing mechanism must be strong in the face of any potential future logic changes to either JSONWriter, JSONStringValueSerializer, PrefHashCalculator. This test protects against that.

As highlighted in code comments these test hashes must never be altered to satisfy a code logic change or PrefHash* breaks.

Kept existing test hashes for list/dict values and expanded the test to all other values.

Review URL: https://codereview.chromium.org/136473008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245576 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245576
Hook up the tsan flag for the GN build.

Add a flag to disable GLIBCXX_DEBUG which is used in the GYP build on some bots.

TBR=scottmg

Review URL: https://codereview.chromium.org/141703004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245577 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245577