Allow removing size callbacks from Targets.

There's a race where a Target can be cleared before a View is laid out. If that happens and the view is laid out later on, we will crash. Removing the callback from the ViewTarget when the Target is cleared resolves that issue.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=155384032

library/src/main/java/com/bumptech/glide/ListPreloader.java

@@ -226,5 +226,10 @@ public void onResourceReady(Object resource, Transition<? super Object> transiti
     public void getSize(SizeReadyCallback cb) {
       cb.onSizeReady(photoWidth, photoHeight);
     }
+
+    @Override
+    public void removeCallback(SizeReadyCallback cb) {
+      // Do nothing because we don't retain references to SizeReadyCallbacks.
+    }
   }
 }

library/src/main/java/com/bumptech/glide/request/RequestFutureTarget.java

@@ -125,6 +125,11 @@ public void getSize(SizeReadyCallback cb) {
     cb.onSizeReady(width, height);
   }
 
+  @Override
+  public void removeCallback(SizeReadyCallback cb) {
+    // Do nothing because we do not retain references to SizeReadyCallbacks.
+  }
+
   /**
    * {@inheritDoc}
    */

library/src/main/java/com/bumptech/glide/request/SingleRequest.java

@@ -238,6 +238,7 @@ && canNotifyStatusChanged()) {
    */
   void cancel() {
     stateVerifier.throwIfRecycled();
+    target.removeCallback(this);
     status = Status.CANCELLED;
     if (loadStatus != null) {
       loadStatus.cancel();

library/src/main/java/com/bumptech/glide/request/target/SimpleTarget.java

@@ -64,4 +64,9 @@ public final void getSize(SizeReadyCallback cb) {
     }
     cb.onSizeReady(width, height);
   }
+
+  @Override
+  public void removeCallback(SizeReadyCallback cb) {
+    // Do nothing, we never retain a reference to the callback.
+  }
 }

library/src/main/java/com/bumptech/glide/request/target/Target.java

@@ -83,6 +83,13 @@ public interface Target<R> extends LifecycleListener {
    */
   void getSize(SizeReadyCallback cb);
 
+  /**
+   * Removes the given callback from the pending set if it's still retained.
+   *
+   * @param cb The callback to remove.
+   */
+  void removeCallback(SizeReadyCallback cb);
+
   /**
    * Sets the current request for this target to retain, should not be called outside of Glide.
    */

library/src/main/java/com/bumptech/glide/request/target/ViewTarget.java

@@ -68,6 +68,11 @@ public void getSize(SizeReadyCallback cb) {
     sizeDeterminer.getSize(cb);
   }
 
+  @Override
+  public void removeCallback(SizeReadyCallback cb) {
+    sizeDeterminer.removeCallback(cb);
+  }
+
   @Override
   public void onLoadCleared(Drawable placeholder) {
     super.onLoadCleared(placeholder);
@@ -214,6 +219,10 @@ void getSize(SizeReadyCallback cb) {
       }
     }
 
+    void removeCallback(SizeReadyCallback cb) {
+      cbs.remove(cb);
+    }
+
     void clearCallbacksAndListener() {
       // Keep a reference to the layout listener and remove it here
       // rather than having the observer remove itself because the observer

library/src/test/java/com/bumptech/glide/request/SingleRequestTest.java

@@ -835,6 +835,11 @@ public void onResourceReady(List resource, Transition<? super List> transition)
     public void getSize(SizeReadyCallback cb) {
     }
 
+    @Override
+    public void removeCallback(SizeReadyCallback cb) {
+      // Do nothing.
+    }
+
     @Override
     public void setRequest(Request request) {
     }