Removes MediaDecoderJob virtual method call from destructor.

This execution path is currently seen used when destroying a
VideoDecoderJob that's still decoding:
* MediaDecoderJob::Release (early return, destroy_pending_=true)
* ...
* MediaDecoderJob::OnDecodeComplete
* ~VideoDecoderJob
* ~MediaDecoderJob
* MediaDecoderJob::ReleaseMediaCodecBridge
* MediaDecoderJob::OnMediaCodecBridgeReleased <-- !!!

The last line should be:
* VideoDecoderJob::OnMediaCodecBridgeReleased

but since it is invoked during the destructor the overridden
implementation is not executed.

R=qinmin@chromium.org,xhwang@chromium.org
BUG=internal b/17671489

Review URL: https://codereview.chromium.org/647553003

Cr-Commit-Position: refs/heads/master@{#299159}

media/base/android/media_decoder_job.cc

@@ -48,7 +48,7 @@ MediaDecoderJob::MediaDecoderJob(
 }
 
 MediaDecoderJob::~MediaDecoderJob() {
-  ReleaseMediaCodecBridge();
+  DCHECK(!media_codec_bridge_);
 }
 
 void MediaDecoderJob::OnDataReceived(const DemuxerData& data) {
@@ -232,6 +232,7 @@ void MediaDecoderJob::Release() {
     return;
   }
 
+  ReleaseMediaCodecBridge();
   delete this;
 }
 
@@ -500,6 +501,7 @@ void MediaDecoderJob::OnDecodeCompleted(
 
   if (destroy_pending_) {
     DVLOG(1) << __FUNCTION__ << " : completing pending deletion";
+    ReleaseMediaCodecBridge();
     delete this;
     return;
   }