[cc] Adds source_id and sequence_number to BeginFrameArgs.

cc/test/fake_external_begin_frame_source.cc

Index: cc/test/fake_external_begin_frame_source.cc
diff --git a/cc/test/fake_external_begin_frame_source.cc b/cc/test/fake_external_begin_frame_source.cc
index 1a15b09b49ab69a2aa0a9233efe04493147cff3b..23051fa32b246bd376446fac37ccfcee37bcc1fb 100644
--- a/cc/test/fake_external_begin_frame_source.cc
+++ b/cc/test/fake_external_begin_frame_source.cc
@@ -65,9 +65,12 @@ bool FakeExternalBeginFrameSource::IsThrottled() const {
 void FakeExternalBeginFrameSource::TestOnBeginFrame(
     const BeginFrameArgs& args) {
   DCHECK(CalledOnValidThread());
+  BeginFrameArgs modified_args = args;
+  modified_args.source_id = source_id();
+  modified_args.sequence_number = next_begin_frame_number_++;
   std::set<BeginFrameObserver*> observers(observers_);
   for (auto* obs : observers)
-    obs->OnBeginFrame(args);
+    obs->OnBeginFrame(modified_args);
   if (tick_automatically_)
     PostTestOnBeginFrame();
 }
@@ -77,10 +80,12 @@ void FakeExternalBeginFrameSource::PostTestOnBeginFrame() {
       base::Bind(&FakeExternalBeginFrameSource::TestOnBeginFrame,
                  weak_ptr_factory_.GetWeakPtr()));
   base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(begin_frame_task_.callback(),
-                 CreateBeginFrameArgsForTesting(BEGINFRAME_FROM_HERE)),
+      FROM_HERE, base::Bind(begin_frame_task_.callback(),
+                            CreateBeginFrameArgsForTesting(
+                                BEGINFRAME_FROM_HERE, source_id(),
+                                next_begin_frame_number_)),
       base::TimeDelta::FromMilliseconds(milliseconds_per_frame_));
+  next_begin_frame_number_++;
 }
 
 }  // namespace cc