Fix flaky cast_unittests where threads were being joined incorrectly.

media/cast/receiver/video_decoder_unittest.cc

 // Copyright 2014 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 <cstdlib>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
@@ skipping 26 matching lines @@
 
 class VideoDecoderTest : public ::testing::TestWithParam<Codec> {
  public:
   VideoDecoderTest()
       : cast_environment_(new StandaloneCastEnvironment()),
         vp8_encoder_(GetVideoSenderConfigForTest(), 0),
         cond_(&lock_) {
     vp8_encoder_.Initialize();
   }
 
+  virtual ~VideoDecoderTest() {
+    // Make sure all threads have stopped before the environment goes away.
+    cast_environment_->Shutdown();
+  }
+
  protected:
   virtual void SetUp() OVERRIDE {
     video_decoder_.reset(new VideoDecoder(cast_environment_, GetParam()));
     CHECK_EQ(STATUS_VIDEO_INITIALIZED, video_decoder_->InitializationResult());
 
     next_frame_timestamp_ = base::TimeDelta();
     last_frame_id_ = 0;
     seen_a_decoded_frame_ = false;
 
     total_video_frames_feed_in_ = 0;
@@ skipping 117 matching lines @@
   }
   WaitForAllVideoToBeDecoded();
 }
 
 INSTANTIATE_TEST_CASE_P(VideoDecoderTestScenarios,
                         VideoDecoderTest,
                         ::testing::Values(CODEC_VIDEO_VP8));
 
 }  // namespace cast
 }  // namespace media