Create EarlGrey wait utility.

ios/web/public/test/web_view_interaction_test_util.mm

Index: ios/web/public/test/web_view_interaction_test_util.mm
diff --git a/ios/web/public/test/web_view_interaction_test_util.mm b/ios/web/public/test/web_view_interaction_test_util.mm
index 896639a0f6e1a17e4c9e92398ce87ad199ffbc13..c5066c7e6fa9092f836dea18ec4ff2a33134473d 100644
--- a/ios/web/public/test/web_view_interaction_test_util.mm
+++ b/ios/web/public/test/web_view_interaction_test_util.mm
@@ -27,14 +27,9 @@ void TapWebViewElementWithId(web::WebState* web_state,
         did_complete = true;
       }));
 
-  // TODO(crbug.com/610837): Re-factor wait code into common location.
-  NSDate* deadline = [NSDate
-      dateWithTimeIntervalSinceNow:testing::kWaitForJSCompletionTimeout];
-  while (([[NSDate date] compare:deadline] != NSOrderedDescending) &&
-         !did_complete) {
-    base::test::ios::SpinRunLoopWithMaxDelay(
-        base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
-  }
+  testing::WaitUntilCondition(testing::kWaitForJSCompletionTimeout, ^() {

[Eugene But (OOO till 7-30), 2016/06/06 21:38:59]

Optional NIT: s/^() {/^{

[baxley, 2016/06/06 22:38:07]

Done.

+    return did_complete;
+  });

[baxley, 2016/06/06 21:20:48]

Let me know what you think of the readability here and if a variable for the
block would be useful. It wouldn't shorten the number of lines, though it may
make it more readable.

[Eugene But (OOO till 7-30), 2016/06/06 21:38:59]

I believe that inline blocks are more readable comparing to using a local
variable for them. This is because Actual code flow is Call Method -> Call block
and local variable reverses this order.

Sometimes however inline blocks make formatting unreadable, but this is
definitely not the case!

[baxley, 2016/06/06 22:38:07]

Acknowledged.

 }
 
 }  // namespace test