SnapdragonGallery: Fix crash show dialog when activity finished

don't show progressDialog when activity is finished

Change-Id: I846430949229f2c3992514a24876fe02ba58a924
diff --git a/src/com/android/gallery3d/filtershow/filters/TrueScannerActs.java b/src/com/android/gallery3d/filtershow/filters/TrueScannerActs.java
index ccce699..6260502 100755
--- a/src/com/android/gallery3d/filtershow/filters/TrueScannerActs.java
+++ b/src/com/android/gallery3d/filtershow/filters/TrueScannerActs.java
@@ -112,8 +112,11 @@
         if (null != sActivity) {
             sActivity.runOnUiThread(new Runnable() {
                 public void run() {
-                    mProgressDialog = ProgressDialog.show(sActivity, "", "Processing...", true, false);
-                    mProgressDialog.show();
+                    if (!sActivity.isFinishing()) {
+                        mProgressDialog = ProgressDialog.show(sActivity,
+                                "", "Processing...", true, false);
+                        mProgressDialog.show();
+                    }
                 }
             });
         }