[Sync] Implement encryption-aware conflict resolution.

chrome/browser/sync/engine/conflict_resolver.h

Index: chrome/browser/sync/engine/conflict_resolver.h
diff --git a/chrome/browser/sync/engine/conflict_resolver.h b/chrome/browser/sync/engine/conflict_resolver.h
index b1cab715eda4cb8e8daf0d199550287be6b35f92..5382f45a5d1a50d6c14e9885ec0c928b19135e52 100644
--- a/chrome/browser/sync/engine/conflict_resolver.h
+++ b/chrome/browser/sync/engine/conflict_resolver.h
@@ -39,6 +39,19 @@ class ConflictResolver {
   FRIEND_TEST_ALL_PREFIXES(SyncerTest,
                            ConflictResolverMergeOverwritesLocalEntry);
  public:
+  // Enumeration of different conflict resolutions. Used for histogramming.
+  enum SimpleConflictResolutions {
+    OVERWRITE_LOCAL,           // Resolved by overwriting local changes.
+    OVERWRITE_SERVER,          // Resolved by overwriting server changes.
+    UNDELETE,                  // Resolved by undeleting local item.
+    IGNORE_ENCRYPTION,         // Resolved by ignoring an encryption-only server
+                               // change.
+    NIGORI_MERGE,              // Resolved by merging nigori nodes.
+    CHANGES_MATCH,             // Resolved by ignoring both local and server
+                               // changes because they matched.
+    CONFLICT_RESOLUTION_SIZE,
+  };
+
   ConflictResolver();
   ~ConflictResolver();
   // Called by the syncer at the end of a update/commit cycle.