DashPlayer:call unregisterHandler in DashPlayer, avoid memory leak

AHandler objects in mediaplayer registred with ALooper
but did not call unregister at shutdown.

Change-Id: If9140d30ace0423c8181a1a64707ddcdc448d525
CRs-Fixed: 461906
diff --git a/dashplayer/DashPlayerDecoder.cpp b/dashplayer/DashPlayerDecoder.cpp
index 180b355..1439560 100644
--- a/dashplayer/DashPlayerDecoder.cpp
+++ b/dashplayer/DashPlayerDecoder.cpp
@@ -41,6 +41,17 @@
 }
 
 DashPlayer::Decoder::~Decoder() {
+    ALooper::handler_id id = 0;
+    if (mCodec != NULL) {
+        id = mCodec->id();
+    }
+    if (id != 0) {
+        if (mCodecLooper != NULL) {
+            mCodecLooper->stop();
+            mCodecLooper->unregisterHandler(id);
+        }
+        looper()->unregisterHandler(id);
+    }
 }
 
 void DashPlayer::Decoder::configure(const sp<MetaData> &meta) {