Adding gtest helpers for BeginFrameArgs.

cc/test/output_test_common.cc

Index: cc/test/output_test_common.cc
diff --git a/cc/test/output_test_common.cc b/cc/test/output_test_common.cc
index 6995796e5e0ff6f98ecc3c46578e9a5197e8c71b..2743755306f2d44e74cf4cf694a17d680889dd37 100644
--- a/cc/test/output_test_common.cc
+++ b/cc/test/output_test_common.cc
@@ -32,4 +32,15 @@ BeginFrameArgs BeginFrameArgsCreateQuick(int64 frame_time,
                                 base::TimeDelta::FromInternalValue(deadline));
 }
 
+bool operator==(BeginFrameArgs lhs, BeginFrameArgs rhs) {
+  return (lhs.frame_time == rhs.frame_time) && (lhs.deadline == rhs.deadline) &&
+         (lhs.interval == rhs.interval);
+}
+
+void PrintTo(const BeginFrameArgs& args, ::std::ostream* os) {
+  *os << "BeginFrameArgs(" << args.frame_time.ToInternalValue() << ", "
+      << args.deadline.ToInternalValue() << ", "
+      << args.interval.InMicroseconds() << "us)";
+}
+
 }  // namespace cc