Use NSS for symmetric key crypto operations on Windows and Mac.

crypto/crypto.gyp

Index: crypto/crypto.gyp
diff --git a/crypto/crypto.gyp b/crypto/crypto.gyp
index fdc0fa9c86ac49e84b893eefb148980d61ba6889..d61184bde10a2307ffabbe6e02cf033b2de3a3ca 100644
--- a/crypto/crypto.gyp
+++ b/crypto/crypto.gyp
@@ -53,10 +53,16 @@
               ['exclude', '_nss\.cc$'],
               ['include', 'ec_private_key_nss\.cc$'],
               ['include', 'ec_signature_creator_nss\.cc$'],
+              ['include', 'encryptor_nss\.cc$'],
+              ['include', 'hmac_nss\.cc$'],
               ['include', 'signature_verifier_nss\.cc$'],
+              ['include', 'symmetric_key_nss\.cc$'],
             ],
             'sources!': [
+              'hmac_win.cc',
               'openpgp_symmetric_encryption.cc',
+              'openpgp_symmetric_encryption.h',
+              'symmetric_key_win.cc',
             ],
         }],
         [ 'OS == "android"', {
@@ -66,7 +72,10 @@
             'sources/': [
               ['exclude', 'ec_private_key_nss\.cc$'],
               ['exclude', 'ec_signature_creator_nss\.cc$'],
+              ['exclude', 'encryptor_nss\.cc$'],
+              ['exclude', 'hmac_nss\.cc$'],
               ['exclude', 'signature_verifier_nss\.cc$'],
+              ['exclude', 'symmetric_key_nss\.cc$'],
             ],
         }],
         [ 'os_bsd==1', {
@@ -96,6 +105,10 @@
             '../third_party/nss/nss.gyp:nspr',
             '../third_party/nss/nss.gyp:nss',
           ],
+          'export_dependent_settings': [
+            '../third_party/nss/nss.gyp:nspr',
+            '../third_party/nss/nss.gyp:nss',
+          ],
         }],
         [ 'OS != "win"', {
           'sources!': [
@@ -163,11 +176,8 @@
         'ec_signature_creator_openssl.cc',
         'encryptor.cc',
         'encryptor.h',
-        'encryptor_mac.cc',
         'encryptor_nss.cc',
         'encryptor_openssl.cc',
-        'encryptor_win.cc',
-        'hmac_mac.cc',
         'hmac_nss.cc',
         'hmac_openssl.cc',
         'keychain_mac.cc',
@@ -208,7 +218,6 @@
         'signature_verifier.h',
         'signature_verifier_nss.cc',
         'signature_verifier_openssl.cc',
-        'symmetric_key_mac.cc',
         'symmetric_key_nss.cc',
         'symmetric_key_openssl.cc',
         'third_party/nss/chromium-blapi.h',
@@ -303,6 +312,7 @@
           ],
           'defines': [
            'CRYPTO_IMPLEMENTATION',
+           '<@(nacl_win64_defines)',
           ],
           'msvs_disabled_warnings': [
             4018,