Delete "external" persistent blobs on cleanup

Also switch external persistent blog directory to cache

Fixes #6909
// FREEBIE

src/org/thoughtcrime/securesms/DatabaseUpgradeActivity.java

@@ -73,6 +73,7 @@ public class DatabaseUpgradeActivity extends BaseActivity {
   public static final int NO_MORE_CANONICAL_DB_VERSION         = 276;
   public static final int PROFILES                             = 289;
   public static final int SCREENSHOTS                          = 300;
+  public static final int PERSISTENT_BLOBS                     = 307;
 
   private static final SortedSet<Integer> UPGRADE_VERSIONS = new TreeSet<Integer>() {{
     add(NO_MORE_KEY_EXCHANGE_PREFIX_VERSION);
@@ -249,6 +250,16 @@ public class DatabaseUpgradeActivity extends BaseActivity {
         TextSecurePreferences.setScreenSecurityEnabled(getApplicationContext(), screenSecurity);
       }
 
+      if (params[0] < PERSISTENT_BLOBS) {
+        File externalDir = context.getExternalFilesDir(null);
+
+        if (externalDir != null && externalDir.isDirectory() && externalDir.exists()) {
+          for (File blob : externalDir.listFiles()) {
+            if (blob.exists() && blob.isFile()) blob.delete();
+          }
+        }
+      }
+
       return null;
     }
 

src/org/thoughtcrime/securesms/providers/PersistentBlobProvider.java

@@ -141,6 +141,10 @@ public class PersistentBlobProvider {
       return getFile(ContentUris.parseId(uri)).delete();
     }
 
+    if (isExternalBlobUri(context, uri)) {
+      return new File(uri.getPath()).delete();
+    }
+
     return false;
   }
 
@@ -219,7 +223,7 @@ public class PersistentBlobProvider {
   }
 
   private static @NonNull File getExternalDir(Context context) throws IOException {
-    final File externalDir = context.getExternalFilesDir(null);
+    final File externalDir = context.getExternalCacheDir();
     if (externalDir == null) throw new IOException("no external files directory");
     return externalDir;
   }