Supply empty frames until codec is done with top-off.

remoting/codec/codec_test.cc

Index: remoting/codec/codec_test.cc
diff --git a/remoting/codec/codec_test.cc b/remoting/codec/codec_test.cc
index 51b52f03ee2358b8073051ba330e61d5bffafde2..3f7b5d496d18e4c68a9702b17f5e5028aaea6788 100644
--- a/remoting/codec/codec_test.cc
+++ b/remoting/codec/codec_test.cc
@@ -284,7 +284,8 @@ void TestVideoEncoder(VideoEncoder* encoder, bool strict) {
   }
 }
 
-void TestVideoEncoderEmptyFrames(VideoEncoder* encoder, int topoff_frames) {
+void TestVideoEncoderEmptyFrames(VideoEncoder* encoder,
+                                 int expected_topoff_frames) {
   const DesktopSize kSize(640, 480);
   scoped_ptr<DesktopFrame> frame(PrepareFrame(kSize));
 
@@ -292,12 +293,15 @@ void TestVideoEncoderEmptyFrames(VideoEncoder* encoder, int topoff_frames) {
       webrtc::DesktopRect::MakeSize(kSize));
   EXPECT_TRUE(encoder->Encode(*frame));
 
+  int topoff_frames = 0;
   frame->mutable_updated_region()->Clear();
-  for (int i=0; i < topoff_frames; ++i) {
-    EXPECT_TRUE(encoder->Encode(*frame));
+  for (int i = 0; i < expected_topoff_frames + 1; ++i) {
+    if (!encoder->Encode(*frame))
+      break;
+    topoff_frames++;
   }
 
-  EXPECT_FALSE(encoder->Encode(*frame));
+  EXPECT_EQ(topoff_frames, expected_topoff_frames);
 }
 
 static void TestEncodeDecodeRects(VideoEncoder* encoder,