Don't abuse LevelDBObserver interface to pass GetAll result.

content/common/leveldb_wrapper.mojom

Index: content/common/leveldb_wrapper.mojom
diff --git a/content/common/leveldb_wrapper.mojom b/content/common/leveldb_wrapper.mojom
index 6295be0b9789a4075e1a7195e418557acb6022c6..e099618c3727e8a5442c9cf388ebf0aaecc61dff 100644
--- a/content/common/leveldb_wrapper.mojom
+++ b/content/common/leveldb_wrapper.mojom
@@ -15,11 +15,6 @@ interface LevelDBObserver {
              string source);
   KeyDeleted(array<uint8> key, array<uint8> old_value, string source);
   AllDeleted(string source);
-
-  // Since the GetAll call is synchronous, observers need this asynchronously
-  // delivered notification to avoid applying changes to the returned array
-  // that it already contains.
-  GetAllComplete(string source);
 };
 
 struct KeyValue {
@@ -27,6 +22,16 @@ struct KeyValue {
   array<uint8> value;
 };
 
+// Since the GetAll call is synchronous, LevelDBWrapper users need this
+// asynchronously delivered notification to avoid applying changes to the
+// returned array that it already contains. This is not sent over the
+// normal LevelDBObserver interface as there can be many observers and
+// only the connection that made the GetAll call needs to be notified of
+// its completion.
+interface LevelDBWrapperGetAllCallback {
+  Complete(bool success);
+};
+
 // A wrapper around leveldb that supports giving notifications when values
 // change.
 interface LevelDBWrapper {
@@ -48,6 +53,6 @@ interface LevelDBWrapper {
 
   // Only used with small databases. Returns all key/value pairs.
   [Sync]
-  GetAll(string source)
+  GetAll(associated LevelDBWrapperGetAllCallback complete_callback)
     => (leveldb.mojom.DatabaseError status, array<KeyValue> data);
 };