minor changes

app/src/main/java/acr/browser/lightning/constant/Constants.java

@@ -8,8 +8,6 @@ import android.support.annotation.IntDef;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 
-import acr.browser.lightning.BuildConfig;
-
 public final class Constants {
 
     private Constants() {

app/src/main/java/acr/browser/lightning/database/downloads/DownloadItem.java

@@ -25,6 +25,7 @@ public class DownloadItem implements Comparable<DownloadItem> {
     public DownloadItem(@NonNull String url, @NonNull String title, @NonNull String size) {
         Preconditions.checkNonNull(url);
         Preconditions.checkNonNull(title);
+        Preconditions.checkNonNull(size);
         this.mUrl = url;
         this.mTitle = title;
         this.mContentSize = size;

app/src/main/java/acr/browser/lightning/database/downloads/DownloadsModel.java

@@ -12,7 +12,7 @@ import java.util.List;
  * The interface that should be used to
  * communicate with the download database.
  * <p>
- * Created by anthonycr on 5/6/17.
+ * Created by df1e on 29/5/17.
  */
 public interface DownloadsModel {
 

app/src/main/java/acr/browser/lightning/dialog/LightningDialogBuilder.java

@@ -16,6 +16,7 @@ import android.widget.AutoCompleteTextView;
 import android.widget.EditText;
 
 import com.anthonycr.bonsai.CompletableOnSubscribe;
+import com.anthonycr.bonsai.CompletableSubscriber;
 import com.anthonycr.bonsai.Schedulers;
 import com.anthonycr.bonsai.SingleOnSubscribe;
 
@@ -39,14 +40,13 @@ import acr.browser.lightning.utils.IntentUtils;
 import acr.browser.lightning.utils.Preconditions;
 import acr.browser.lightning.utils.Utils;
 
-import static android.content.ContentValues.TAG;
-
 /**
  * TODO Rename this class it doesn't build dialogs only for bookmarks
  * <p/>
  * Created by Stefano Pacifici on 02/09/15, based on Anthony C. Restaino's code.
  */
 public class LightningDialogBuilder {
+    public static final String TAG = "LightningDialogBuilder";
 
     public enum NewTab {
         FOREGROUND,
@@ -173,8 +173,15 @@ public class LightningDialogBuilder {
             new BrowserDialog.Item(R.string.dialog_delete_all_downloads) {
                 @Override
                 public void onClick() {
-                    mDownloadsModel.deleteAllDownloads().subscribeOn(Schedulers.io()).subscribe();
-                    uiController.handleDownloadDeleted();
+                    mDownloadsModel.deleteAllDownloads()
+                            .subscribeOn(Schedulers.io())
+                            .observeOn(Schedulers.main())
+                            .subscribe(new CompletableOnSubscribe() {
+                                @Override
+                                public void onComplete() {
+                                    uiController.handleDownloadDeleted();
+                                }
+                            });
                 }
             });
     }

app/src/main/java/acr/browser/lightning/view/LightningWebClient.java

@@ -22,7 +22,6 @@ import android.view.View;
 import android.webkit.HttpAuthHandler;
 import android.webkit.MimeTypeMap;
 import android.webkit.SslErrorHandler;
-import android.webkit.URLUtil;
 import android.webkit.ValueCallback;
 import android.webkit.WebResourceRequest;
 import android.webkit.WebResourceResponse;
@@ -360,8 +359,8 @@ public class LightningWebClient extends WebViewClient {
                 }
                 return true;
             }
-        } else if (url.startsWith("file://")) {
-            File file = new File(url.replace("file://", ""));
+        } else if (url.startsWith(Constants.FILE)) {
+            File file = new File(url.replace(Constants.FILE, ""));
 
             if (file.exists()) {
                 String newMimeType = MimeTypeMap.getSingleton()