修复图片全屏浏览时的返回按钮响应。

app/src/main/java/cc/winboll/gallery/ImageViewerActivity.java

@@ -75,10 +75,6 @@ public class ImageViewerActivity extends Activity implements ViewPager.OnPageCha
     
     @Override
     public void onBackPressed() {
-        if (viewPager.getCurrentItem() > 0) {
-            viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
-        } else {
-            super.onBackPressed();
-        }
+        finish();
     }
 }