Pass (snapshot object) to customize_snapshot_save filter.

php/class-customize-snapshot.php

@@ -294,10 +294,11 @@ public function save( array $args ) {
 		/**
 		 * Filter the snapshot's data before it's saved to 'post_content'.
 		 *
-		 * @param array $data Customizer snapshot data, with setting IDs mapped to an array
-		 *                    containing a `value` array item and potentially other metadata.
+		 * @param array              $data Customizer snapshot data, with setting IDs mapped to an array
+		 *                                 containing a `value` array item and potentially other metadata.
+		 * @param Customize_Snapshot $this Snapshot object.
 		 */
-		$this->data = apply_filters( 'customize_snapshot_save', $this->data );
+		$this->data = apply_filters( 'customize_snapshot_save', $this->data, $this );
 
 		$result = $this->snapshot_manager->post_type->save( array_merge(
 			$args,

tests/php/test-class-customize-snapshot.php

@@ -114,6 +114,7 @@ function tearDown() {
 		$this->wp_customize = null;
 		unset( $GLOBALS['wp_customize'] );
 		unset( $GLOBALS['wp_scripts'] );
+		$this->filtered_snapshot = null;
 		parent::tearDown();
 	}
 
@@ -323,4 +324,37 @@ function test_saved() {
 			'data' => array( 'foo' => array( 'value' => 'bar' ) ),
 		) );
 	}
+
+	/**
+	 * Snapshot object passed in customize_snapshot_save filter.
+	 *
+	 * @var Customize_Snapshot
+	 */
+	public $filtered_snapshot;
+
+	/**
+	 * Test that the snapshot object is passed as the second filter param.
+	 *
+	 * @see Customize_Snapshot::save()
+	 */
+	function test_filter_customize_snapshot_save() {
+		$manager = new Customize_Snapshot_Manager( $this->plugin );
+		$manager->ensure_customize_manager();
+		$manager->init();
+
+		$snapshot = new Customize_Snapshot( $manager, self::UUID );
+
+		$that = $this; // For PHP 5.3.
+		add_filter( 'customize_snapshot_save', function( $data, $test_snapshot ) use ( $that ) {
+			$that->filtered_snapshot = $test_snapshot;
+			return $data;
+		}, 10, 2 );
+
+		$snapshot->save( array(
+			'uuid' => self::UUID,
+			'data' => array( 'foo' => array( 'value' => 'bar' ) ),
+		) );
+
+		$this->assertEquals( $snapshot, $this->filtered_snapshot );
+	}
 }