Android: Remove @MainDex from SelectFileDialog

It's used only by the browser process, so doesn't need to be in the main
dex.

Bug: 820570
Change-Id: I3f02e1f2d1255452f474db306e68583f8c7200e6
Reviewed-on: https://chromium-review.googlesource.com/971343
Commit-Queue: Peter Beverloo <peter@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544706}

ui/android/java/src/org/chromium/ui/base/SelectFileDialog.java

@@ -28,7 +28,6 @@ import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
-import org.chromium.base.annotations.MainDex;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.ui.PhotoPickerListener;
 import org.chromium.ui.R;
@@ -46,7 +45,6 @@ import java.util.concurrent.TimeUnit;
  * a set of accepted file types. The path of the selected file is passed to the native dialog.
  */
 @JNINamespace("ui")
-@MainDex
 public class SelectFileDialog implements WindowAndroid.IntentCallback,
                                          WindowAndroid.PermissionCallback, PhotoPickerListener {
     private static final String TAG = "SelectFileDialog";