Split CrOS-specific TPM, etc., code into a separate file

It's still in //crypto, but now it's a bit more self-contained.

Bug: 125848
Change-Id: I8596aa9f66630625234206986636edcb29853c73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857046
Commit-Queue: David Benjamin <[email protected]>
Reviewed-by: Matt Mueller <[email protected]>
Cr-Commit-Position: refs/heads/master@{#706202}
diff --git a/crypto/BUILD.gn b/crypto/BUILD.gn
index c27c7cf..0eab491 100644
--- a/crypto/BUILD.gn
+++ b/crypto/BUILD.gn
@@ -116,6 +116,10 @@
     ]
   }
 
+  if (is_chromeos) {
+    sources += [ "nss_util_chromeos.cc" ]
+  }
+
   defines = [ "CRYPTO_IMPLEMENTATION" ]
 
   if (is_nacl) {