Ensure link preview fetches are canceled on message send.

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java

@@ -2366,6 +2366,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
     attachmentManager.cleanup();
 
     updateLinkPreviewState();
+    linkPreviewViewModel.onSend();
   }
 
   private void sendMessage() {

app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java

@@ -90,7 +90,11 @@ public class LinkPreviewViewModel extends ViewModel {
         Util.runOnMain(() -> {
           if (!userCanceled) {
             if (lp.isPresent()) {
-              linkPreviewState.setValue(LinkPreviewState.forPreview(lp.get()));
+              if (activeUrl != null && activeUrl.equals(lp.get().getUrl())) {
+                linkPreviewState.setValue(LinkPreviewState.forPreview(lp.get()));
+              } else {
+                linkPreviewState.setValue(LinkPreviewState.forNoLinks());
+              }
             } else {
               linkPreviewState.setValue(LinkPreviewState.forLinksWithNoPreview());
             }
@@ -114,6 +118,19 @@ public class LinkPreviewViewModel extends ViewModel {
     linkPreviewState.setValue(LinkPreviewState.forNoLinks());
   }
 
+  public void onSend() {
+    if (activeRequest != null) {
+      activeRequest.cancel();
+      activeRequest = null;
+    }
+
+    userCanceled = false;
+    activeUrl    = null;
+
+    debouncer.clear();
+    linkPreviewState.setValue(LinkPreviewState.forNoLinks());
+  }
+
   public void onEnabled() {
     userCanceled = false;
   }