Fix flakiness of SyncFakeServerTestCase.testSyncTypedURLDeleteFromServer

The test was flaky because after triggering sync cycle it immediately checked
for entity count condition without waiting for sync cycle to complete. I've
verified that test fails consistently after adding delay in sync cycle.

I've added WaitUntilConditionOrTimeout.

BUG=672286
R=bzanotti@chromium.org

Review-Url: https://codereview.chromium.org/2610303002
Cr-Commit-Position: refs/heads/master@{#441703}

ios/chrome/browser/ui/sync/sync_fake_server_egtest.mm

@@ -112,6 +112,24 @@ void AssertNumberOfEntities(int entity_count, syncer::ModelType entity_type) {
       testing::WaitUntilConditionOrTimeout(kSyncOperationTimeout, condition),
       @"Expected %d entities of the specified type", entity_count);
 }
+
+// Waits for |entity_count| entities of type |entity_type| with name |name|, and
+// fails with a GREYAssert if the condition is not met, within a short period of
+// time.
+void AssertNumberOfEntitiesWithName(int entity_count,
+                                    syncer::ModelType entity_type,
+                                    std::string name) {
+  ConditionBlock condition = ^{
+    NSError* error = nil;
+    BOOL success = chrome_test_util::VerifyNumberOfSyncEntitiesWithName(
+        entity_type, name, entity_count, &error);
+    DCHECK(success || error);
+    return !!success;
+  };
+  GREYAssert(
+      testing::WaitUntilConditionOrTimeout(kSyncOperationTimeout, condition),
+      @"Expected %d entities of the specified type", entity_count);
+}
 }  // namespace
 
 // Hermetic sync tests, which use the fake sync server.
@@ -534,7 +552,7 @@ void AssertNumberOfEntities(int entity_count, syncer::ModelType entity_type) {
 
 // Test that typed url is deleted from client after server sends tombstone for
 // that typed url.
-- (void)FLAKY_testSyncTypedURLDeleteFromServer {
+- (void)testSyncTypedURLDeleteFromServer {
   const GURL mockURL("http://not-a-real-site/");
 
   chrome_test_util::ClearBrowsingHistory();
@@ -553,17 +571,12 @@ void AssertNumberOfEntities(int entity_count, syncer::ModelType entity_type) {
   AssertSyncInitialized(YES);
   chrome_test_util::TriggerSyncCycle(syncer::TYPED_URLS);
 
-  NSError* error = nil;
-  BOOL success = chrome_test_util::VerifyNumberOfSyncEntitiesWithName(
-      syncer::TYPED_URLS, mockURL.spec(), 1, &error);
-  DCHECK(success || error);
-  GREYAssertTrue(success, [error localizedDescription]);
+  AssertNumberOfEntitiesWithName(1, syncer::TYPED_URLS, mockURL.spec());
 
   chrome_test_util::DeleteTypedUrlFromClient(mockURL);
 
   // Trigger sync and wait for fake server to be updated.
   chrome_test_util::TriggerSyncCycle(syncer::TYPED_URLS);
-
   __block NSError* blockSafeError = nil;
   GREYCondition* condition = [GREYCondition
       conditionWithName:@"Wait for typed URL to be downloaded."
@@ -574,7 +587,7 @@ void AssertNumberOfEntities(int entity_count, syncer::ModelType entity_type) {
                     blockSafeError = [error copy];
                     return result;
                   }];
-  success = [condition waitWithTimeout:kSyncOperationTimeout];
+  BOOL success = [condition waitWithTimeout:kSyncOperationTimeout];
   DCHECK(success || blockSafeError);
   if (blockSafeError) {
     [blockSafeError autorelease];