Clear webapp storage when site data is cleared

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
index fe19baaa4b8a989dac549b7ba1c400cbc802d928..a4b30b6a1c4ffa82498e4c08a42fc002dedba31d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java
@@ -8,6 +8,9 @@ import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.AsyncTask;
 
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.annotations.CalledByNative;
+
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
@@ -73,6 +76,20 @@ public class WebappRegistry {
         }.execute();
     }
 
+    @CalledByNative
+    public static void cleanupWebappsInBackground(Context context) {

[mlamouri (slow - plz ping), 2015/09/08 10:03:00]

nit: call it "unregisterAllWebapps" to keep it in sync with registerWebapp()?

[Lalit Maganti, 2015/09/08 10:44:28]

Done but kept inBackground because of the assert.

+        assert !ThreadUtils.runningOnUiThread();
+
+        SharedPreferences preferences = context.getSharedPreferences(
+                REGISTRY_FILE_NAME, Context.MODE_PRIVATE);
+        Set<String> webapps = preferences.getStringSet(
+                KEY_WEBAPP_SET, Collections.<String>emptySet());

[mlamouri (slow - plz ping), 2015/09/08 10:03:00]

These four lines seem to be a common pattern. Is there a way you can refactor
that?

[Lalit Maganti, 2015/09/08 10:44:28]

Done.

+        for (String id : webapps) {
+            WebappDataStorage.delete(context, id);
+        }
+        preferences.edit().clear().commit();
+    }
+
     private WebappRegistry() {
     }