Sharing images from internal storage using FileProvider

I have some files stored in my application's internal storage that I would like to open in an external application (sending an image to the Gallery for viewing, for example.) I've set up a FileProvider to do so.

From AndroidManifest.xml:

<application>  ...<provider        android:name="android.support.v4.content.FileProvider"        android:authorities="${packageName}"        android:exported="false"        android:grantUriPermissions="true"><meta-data            android:name="android.support.FILE_PROVIDER_PATHS"            android:resource="@xml/files"/></provider></application>

From res/xml/files.xml:

<paths><files-path name="internal_logs" path="logs/"/><files-path name="shared_files" path="shared/"/></paths>

From the Fragment where I attempt to open the file:

File sharedFolderPath = new File(getActivity().getFilesDir(), "shared");File toOpen = new File(sharedFolderPath.getAbsolutePath(), sharedFile.getFileName());if (toOpen.exists()) {    Log.w("File exists: "+ toOpen.getAbsolutePath());    Uri fileUri = FileProvider.getUriForFile(getActivity(), BuildConfig.PACKAGE_NAME, toOpen);    Log.w("Attempting to attach file "+ fileUri.getEncodedPath() +" with mime type: "+ URLConnection.guessContentTypeFromName(fileUri.toString()));    Intent viewFile = new Intent(Intent.ACTION_VIEW);    viewFile.setData(fileUri);    viewFile.setType(URLConnection.guessContentTypeFromName(fileUri.toString()));    viewFile.putExtra(Intent.EXTRA_STREAM, fileUri);    viewFile.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);    viewFile.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);    try {        startActivity(viewFile);    } catch (android.content.ActivityNotFoundException ex) {        Toast.makeText(getActivity(), "Please install an appropriate application to open this file.", Toast.LENGTH_SHORT).show();    }} else {    log.w("File does not exist: "+ toOpen.getAbsolutePath());    Toast.makeText(getActivity(), "file not found.", Toast.LENGTH_SHORT).show();}

From the logcat output (sharing to the Gallery app):

PACKAGE_NAME W/TAG: File exists: /data/data/PACKAGE_NAME/files/shared/IMG_20140506_141221.jpgPACKAGE_NAME W/TAG: Attempting to attach file /shared_files/IMG_20140506_141221.jpg with mime type: image/jpeg778-791/? I/PackageManager﹕ Action: "android.intent.action.VIEW"778-791/? I/PackageManager﹕ Category: "android.intent.category.DEFAULT"778-791/? I/PackageManager﹕ Type: "image/jpeg"778-791/? I/PackageManager﹕ Adding preferred activity ComponentInfo{com.google.android.gallery3d/com.android.gallery3d.app.GalleryActivity} for user 0 :778-788/? I/ActivityManager﹕ START u0 {act=android.intent.action.VIEW typ=image/jpeg flg=0x3000001 cmp=com.google.android.gallery3d/com.android.gallery3d.app.GalleryActivity (has extras)} from pid 6209778-1872/? I/ActivityManager﹕ Start proc com.google.android.gallery3d for activity com.google.android.gallery3d/com.android.gallery3d.app.GalleryActivity: pid=10602 uid=10039 gids={50039, 3003, 1028, 1015}10602-10602/? V/StateManager﹕ startState class com.android.gallery3d.app.AlbumSetPage

What's happening is that the file is found, a URI is generated, and the mimetype is detected correctly; I get an accurate list of handlers from Android, and when I choose "Gallery", the Gallery activity is launched, but it goes straight to the device's own gallery - no error message, but also no open image. This behavior seems consistent with other image viewers - G+ Photos for example.

The really strange thing is if I execute the same code with the Intent ACTION_SEND declared, the file correctly attaches to an email in Gmail. (In fact, this is what I do with my app's internal logging.) So it seems really unlikely that I'm formatting the content URI incorrectly. My best guess is that I'm using the wrong Intent action? But I have no idea what would be better than ACTION_VIEW.

Any ideas?