Use sqlite transaction listeners (rather than doing so manually)

Using sqlite's version allows us to not worry about getting the
transaction semantics correct in the face of exceptions.

Author: rsgowman

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLiteLruReferenceDelegate.java

@@ -16,14 +16,16 @@
 
 import static com.google.firebase.firestore.util.Assert.hardAssert;
 
+import android.database.sqlite.SQLiteTransactionListener;
 import android.util.SparseArray;
 import com.google.firebase.firestore.core.ListenSequence;
 import com.google.firebase.firestore.model.DocumentKey;
 import com.google.firebase.firestore.model.ResourcePath;
 import com.google.firebase.firestore.util.Consumer;
 
 /** Provides LRU functionality for SQLite persistence. */
-class SQLiteLruReferenceDelegate implements ReferenceDelegate, LruDelegate {
+class SQLiteLruReferenceDelegate
+    implements ReferenceDelegate, LruDelegate, SQLiteTransactionListener {
   private final SQLitePersistence persistence;
   private ListenSequence listenSequence;
   private long currentSequenceNumber;
@@ -40,6 +42,19 @@ void start(long highestSequenceNumber) {
     listenSequence = new ListenSequence(highestSequenceNumber);
   }
 
+  @Override
+  public void onBegin() {
+    onTransactionStarted();
+  }
+
+  @Override
+  public void onCommit() {
+    onTransactionCommitted();
+  }
+
+  @Override
+  public void onRollback() {}
+
   @Override
   public void onTransactionStarted() {
     hardAssert(

firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLitePersistence.java

@@ -144,8 +144,7 @@ RemoteDocumentCache getRemoteDocumentCache() {
   @Override
   void runTransaction(String action, Runnable operation) {
     Logger.debug(TAG, "Starting transaction: %s", action);
-    referenceDelegate.onTransactionStarted();
-    db.beginTransaction();
+    db.beginTransactionWithListener(referenceDelegate);
     try {
       operation.run();
 
@@ -154,15 +153,13 @@ void runTransaction(String action, Runnable operation) {
     } finally {
       db.endTransaction();
     }
-    referenceDelegate.onTransactionCommitted();
   }
 
   @Override
   <T> T runTransaction(String action, Supplier<T> operation) {
     Logger.debug(TAG, "Starting transaction: %s", action);
     T value = null;
-    referenceDelegate.onTransactionStarted();
-    db.beginTransaction();
+    db.beginTransactionWithListener(referenceDelegate);
     try {
       value = operation.get();
 
@@ -171,7 +168,6 @@ <T> T runTransaction(String action, Supplier<T> operation) {
     } finally {
       db.endTransaction();
     }
-    referenceDelegate.onTransactionCommitted();
     return value;
   }