[Sync] Add intelligent re-encryption support.

chrome/browser/sync/internal_api/sync_manager.cc

Index: chrome/browser/sync/internal_api/sync_manager.cc
diff --git a/chrome/browser/sync/internal_api/sync_manager.cc b/chrome/browser/sync/internal_api/sync_manager.cc
index dab01337a988dfac82d7b50fb1b83e60afdf1348..fef46209c8a23f59dc035bb1b2519364bbc8a088 100644
--- a/chrome/browser/sync/internal_api/sync_manager.cc
+++ b/chrome/browser/sync/internal_api/sync_manager.cc
@@ -1066,18 +1066,19 @@ void SyncManager::SyncInternal::SetPassphrase(
       return;
 
     cryptographer->AddKey(params);
-
-    // TODO(tim): Bug 58231. It would be nice if SetPassphrase didn't require
-    // messing with the Nigori node, because we can't call SetPassphrase until
-    // download conditions are met vs Cryptographer init.  It seems like it's
-    // safe to defer this work.
-    sync_pb::NigoriSpecifics specifics(node.GetNigoriSpecifics());
-    specifics.clear_encrypted();
-    cryptographer->GetKeys(specifics.mutable_encrypted());
-    specifics.set_using_explicit_passphrase(is_explicit);
-    node.SetNigoriSpecifics(specifics);
   }
 
+  // TODO(tim): Bug 58231. It would be nice if SetPassphrase didn't require

[akalin, 2011/12/06 18:28:02]

any reason why you moved this out of the if statement?  Maybe mention it in the
CL description.

[Nicolas Zea, 2011/12/06 20:45:36]

To ensure we always have the full set of keys, now that we don't need to worry
about unnecessary changes. This becomes more relevant during nigori conflicts
(which are handled in a separate CL). Updated CL description.

+  // messing with the Nigori node, because we can't call SetPassphrase until
+  // download conditions are met vs Cryptographer init.  It seems like it's
+  // safe to defer this work.
+  sync_pb::NigoriSpecifics specifics(node.GetNigoriSpecifics());
+  // Does not modify specifics.encrypted() if the original decrypted data was
+  // the same.
+  cryptographer->GetKeys(specifics.mutable_encrypted());

[akalin, 2011/12/06 18:28:02]

check return value?

[Nicolas Zea, 2011/12/06 20:45:36]

Done.

+  specifics.set_using_explicit_passphrase(is_explicit);
+  node.SetNigoriSpecifics(specifics);
+
   // Does nothing if everything is already encrypted or the cryptographer has
   // pending keys.
   ReEncryptEverything(&trans);
@@ -1138,8 +1139,6 @@ void SyncManager::SyncInternal::RefreshEncryption() {
   ReEncryptEverything(&trans);
 }
 
-// TODO(zea): Add unit tests that ensure no sync changes are made when not
-// needed.
 void SyncManager::SyncInternal::ReEncryptEverything(WriteTransaction* trans) {
   Cryptographer* cryptographer = trans->GetCryptographer();
   if (!cryptographer || !cryptographer->is_ready())