simplify Downloader constructors

Since all Downloaders are created via the DownloaderFactory, put the temp
file creation there, then we can remove lots of constructors.

F-Droid/src/org/fdroid/fdroid/net/Downloader.java

@@ -2,7 +2,6 @@ package org.fdroid.fdroid.net;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
 import android.util.Log;
 
 import org.fdroid.fdroid.ProgressListener;
@@ -33,29 +32,12 @@ public abstract class Downloader {
 
     public abstract InputStream getInputStream() throws IOException;
 
-    // The context is required for opening the file to write to.
-    Downloader(String destFile, @NonNull Context ctx)
-            throws FileNotFoundException, MalformedURLException {
-        this(new File(ctx.getFilesDir() + File.separator + destFile));
-    }
-
-    // The context is required for opening the file to write to.
-    Downloader(@NonNull Context ctx) throws IOException {
-        this(File.createTempFile("dl-", "", ctx.getCacheDir()));
-    }
-
     Downloader(File destFile)
             throws FileNotFoundException, MalformedURLException {
         outputFile = destFile;
         outputStream = new FileOutputStream(outputFile);
     }
 
-    Downloader(OutputStream output)
-            throws MalformedURLException {
-        outputStream = output;
-        outputFile   = null;
-    }
-
     public void setProgressListener(ProgressListener listener) {
         setProgressListener(listener, null);
     }

F-Droid/src/org/fdroid/fdroid/net/DownloaderFactory.java

@@ -7,12 +7,17 @@ import java.io.IOException;
 
 public class DownloaderFactory {
 
+    /**
+     * Downloads to a temporary file, which *you must delete yourself when
+     * you are done
+     */
     public static Downloader create(String url, Context context)
             throws IOException {
+        File destFile = File.createTempFile("dl-", "", context.getCacheDir());
         if (isOnionAddress(url)) {
-            return new TorHttpDownloader(url, context);
+            return new TorHttpDownloader(url, destFile);
         }
-        return new HttpDownloader(url, context);
+        return new HttpDownloader(url, destFile);
     }
 
     public static Downloader create(String url, File destFile)

F-Droid/src/org/fdroid/fdroid/net/HttpDownloader.java

@@ -1,6 +1,5 @@
 package org.fdroid.fdroid.net;
 
-import android.content.Context;
 import android.util.Log;
 
 import org.fdroid.fdroid.Preferences;
@@ -34,16 +33,6 @@ public class HttpDownloader extends Downloader {
         sourceUrl = new URL(source);
     }
 
-    /**
-     * Downloads to a temporary file, which *you must delete yourself when
-     * you are done*.
-     * @see org.fdroid.fdroid.net.Downloader#getFile()
-     */
-    HttpDownloader(String source, Context ctx) throws IOException {
-        super(ctx);
-        sourceUrl = new URL(source);
-    }
-
     @Override
     public InputStream getInputStream() throws IOException {
         setupConnection();

F-Droid/src/org/fdroid/fdroid/net/TorHttpDownloader.java

@@ -1,7 +1,5 @@
 package org.fdroid.fdroid.net;
 
-import android.content.Context;
-
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
@@ -13,10 +11,6 @@ import java.net.SocketAddress;
 
 public class TorHttpDownloader extends HttpDownloader {
 
-    TorHttpDownloader(String url, Context ctx) throws IOException {
-        super(url, ctx);
-    }
-
     TorHttpDownloader(String url, File destFile)
             throws FileNotFoundException, MalformedURLException {
         super(url, destFile);