Implementing perf tests for foreign key constraints.

The same dataset is tested in three different configurations,
1) No foreign key constraints
2) Immediate foreign key constraints
3) Deferrable foreign key constraints.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=97788835

Author: freshp86

perf/lf_perf_test.js

@@ -18,9 +18,11 @@ goog.setTestOnly();
 goog.require('goog.Promise');
 goog.require('goog.testing.AsyncTestCase');
 goog.require('goog.testing.jsunit');
+goog.require('lf.ConstraintTiming');
 goog.require('lf.schema.DataStoreType');
 goog.require('lf.testing.Capability');
 goog.require('lf.testing.perf.BenchmarkRunner');
+goog.require('lf.testing.perf.ForeignKeysBenchmark');
 goog.require('lf.testing.perf.FullTableBenchmark');
 goog.require('lf.testing.perf.LoadingEmptyDbBenchmark');
 goog.require('lf.testing.perf.LoadingPopulatedDbBenchmark');
@@ -270,3 +272,27 @@ function test6ScenarioSimulations() {
     }, fail);
   }, fail);
 }
+
+
+function test7ForeignKeys() {
+  asyncTestCase.waitForAsync('test7ForeignKeys');
+
+  goog.Promise.all([
+    lf.testing.perf.ForeignKeysBenchmark.create(
+        lf.ConstraintTiming.IMMEDIATE),
+    lf.testing.perf.ForeignKeysBenchmark.create(
+        lf.ConstraintTiming.DEFERRABLE),
+    lf.testing.perf.ForeignKeysBenchmark.create(null)
+  ]).then(function(benchmarks) {
+    var benchmarkRunner = new lf.testing.perf.BenchmarkRunner(
+        'ForeignKeysBenchmark');
+    benchmarks.forEach(function(benchmark) {
+      benchmarkRunner.schedule(benchmark);
+    });
+
+    return benchmarkRunner.run(REPETITIONS);
+  }).then(function(results) {
+    overallResults.push(results);
+    asyncTestCase.continueTesting();
+  }, fail);
+}