Fix exception when setting DownloadCallback in builds before 83.

This regressed in r753679.

Bug: 1066387, 1025603
Change-Id: I77702548bbf7d7606f4f4a9a3f5007e9773f193a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2130347
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Auto-Submit: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755036}

weblayer/public/java/org/chromium/weblayer/Profile.java

@@ -213,7 +213,7 @@ public class Profile {
         return mCookieManager;
     }
 
-    private static final class DownloadCallbackClientImpl extends IDownloadCallbackClient.Stub {
+    static final class DownloadCallbackClientImpl extends IDownloadCallbackClient.Stub {
         private final DownloadCallback mCallback;
 
         DownloadCallbackClientImpl(DownloadCallback callback) {

weblayer/public/java/org/chromium/weblayer/Tab.java

@@ -44,6 +44,7 @@ public class Tab {
     private final FindInPageController mFindInPageController;
     private final ObserverList<TabCallback> mCallbacks;
     private Browser mBrowser;
+    private Profile.DownloadCallbackClientImpl mDownloadCallbackClient;
     private FullscreenCallbackClientImpl mFullscreenCallbackClient;
     private NewTabCallback mNewTabCallback;
     // Id from the remote side.
@@ -111,12 +112,21 @@ public class Tab {
     }
 
     /**
-     * Deprecated. Use Profile.setDownloadCallback instead. For now this works by always using
-     * the last DownloadCallback that has been set by any tab in the same Profile.
+     * Deprecated. Use Profile.setDownloadCallback instead.
      */
     public void setDownloadCallback(@Nullable DownloadCallback callback) {
         ThreadCheck.ensureOnUiThread();
-        mBrowser.getProfile().setDownloadCallback(callback);
+        try {
+            if (callback != null) {
+                mDownloadCallbackClient = new Profile.DownloadCallbackClientImpl(callback);
+                mImpl.setDownloadCallbackClient(mDownloadCallbackClient);
+            } else {
+                mDownloadCallbackClient = null;
+                mImpl.setDownloadCallbackClient(null);
+            }
+        } catch (RemoteException e) {
+            throw new APICallException(e);
+        }
     }
 
     public void setErrorPageCallback(@Nullable ErrorPageCallback callback) {