ppapi: fix crash/infinite loop in VideoEncoder

ppapi/proxy/video_encoder_resource_unittest.cc

Index: ppapi/proxy/video_encoder_resource_unittest.cc
diff --git a/ppapi/proxy/video_encoder_resource_unittest.cc b/ppapi/proxy/video_encoder_resource_unittest.cc
index d908d73ae4e4f14136b6d41c201ea4356461254d..c1d39084d5863b9914d0e146f322afe3e139efcc 100644
--- a/ppapi/proxy/video_encoder_resource_unittest.cc
+++ b/ppapi/proxy/video_encoder_resource_unittest.cc
@@ -1136,6 +1136,14 @@ TEST_F(VideoEncoderResourceTest, Close) {
     ASSERT_EQ(PP_ERROR_ABORTED, encode_cb2.result());
     ASSERT_TRUE(get_bitstream_buffer_cb.called());
     ASSERT_EQ(PP_ERROR_ABORTED, get_bitstream_buffer_cb.result());
+
+    // Verify that a remaining encode response from the renderer is
+    // discarded.
+    ResourceMessageCallParams params;
+    uint32_t frame_id;
+    bool force_frame;
+    ASSERT_TRUE(CheckEncodeMsg(&params, &frame_id, &force_frame));
+    SendEncodeReply(params, frame_id);
   }
 }