Clear up BaseRenderer.disable

- Call onDisabled last. onDisabled really shouldn't be doing
  anything with the stream, so pretty sure this is fine (and
  guarantees the stream is cleared properly even if onDisabled
  throws a RTE).
- Remove super.onDisabled calls from Text/Metadata renderers.
  This is just for consistency; we don't make such calls in
  other direct descendants of BaseRenderer.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=156130640

library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java

@@ -142,9 +142,9 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   public final void disable() {
     Assertions.checkState(state == STATE_ENABLED);
     state = STATE_DISABLED;
-    onDisabled();
     stream = null;
     streamIsFinal = false;
+    onDisabled();
   }
 
   // RendererCapabilities implementation.
@@ -300,8 +300,6 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
 
   /**
    * Returns whether the upstream source is ready.
-   *
-   * @return Whether the source is ready.
    */
   protected final boolean isSourceReady() {
     return readEndOfStream ? streamIsFinal : stream.isReady();

library/core/src/main/java/com/google/android/exoplayer2/metadata/MetadataRenderer.java

@@ -153,7 +153,6 @@ public final class MetadataRenderer extends BaseRenderer implements Callback {
   protected void onDisabled() {
     flushPendingMetadata();
     decoder = null;
-    super.onDisabled();
   }
 
   @Override

library/core/src/main/java/com/google/android/exoplayer2/text/TextRenderer.java

@@ -254,7 +254,6 @@ public final class TextRenderer extends BaseRenderer implements Callback {
     streamFormat = null;
     clearOutput();
     releaseDecoder();
-    super.onDisabled();
   }
 
   @Override