ppapi: fix crash/infinite loop in VideoEncoder

ppapi/proxy/video_encoder_resource_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/memory/shared_memory.h"
 #include "base/process/process.h"
 #include "base/synchronization/waitable_event.h"
 #include "ppapi/c/pp_codecs.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppb_video_encoder.h"
@@ skipping 1118 matching lines @@
                                      &get_bitstream_buffer_cb));
 
     CallClose(encoder.get());
 
     ASSERT_TRUE(encode_cb1.called());
     ASSERT_EQ(PP_ERROR_ABORTED, encode_cb1.result());
     ASSERT_TRUE(encode_cb2.called());
     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);
   }
 }
 
 }  // namespace proxy
 }  // namespace ppapi