Bug 1294629 - Simplify the code of ReaderSuspendedChanged(). r=kaku

SetDormant() checks IsShutdown() and |mState == DECODER_STATE_DORMANT|.
So ReaderSuspendedChanged() can just call SetDormant(mIsReaderSuspended) to do the work.

MozReview-Commit-ID: J7Dzsm8IhIS

--HG--
extra : rebase_source : c8a0bc31071bfbe084c2a5f47821c0dc3cfd0860

dom/media/MediaDecoderStateMachine.cpp

@@ -1400,15 +1400,7 @@ void MediaDecoderStateMachine::ReaderSuspendedChanged()
 {
   MOZ_ASSERT(OnTaskQueue());
   DECODER_LOG("ReaderSuspendedChanged: %d", mIsReaderSuspended.Ref());
-
-  if (IsShutdown()) {
-    return;
-  }
-  if (mIsReaderSuspended && mState != DECODER_STATE_DORMANT) {
-    SetDormant(true);
-  } else if (!mIsReaderSuspended && mState == DECODER_STATE_DORMANT) {
-    SetDormant(false);
-  }
+  SetDormant(mIsReaderSuspended);
 }
 
 void