Store URLs in WebappDataStorage, and purge them when history is cleared.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java
index a7fd579268f336d49bf383d1bfee84165fa57f37..d06f072b63f0a3f37c4d192a1405c50f92df9d63 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java
@@ -31,7 +31,13 @@ public class WebappDataStorage {
     static final String SHARED_PREFS_FILE_PREFIX = "webapp_";
     static final String KEY_SPLASH_ICON = "splash_icon";
     static final String KEY_LAST_USED = "last_used";
+    static final String KEY_ORIGIN_URL = "origin_url";
+
+    // Null/invalid constants for last used times and origins. 0 is used as the null last used time
+    // as WebappRegistry assumes that this is always a valid timestamp.
+    static final long NULL_LAST_USED = 0;

[gone, 2016/03/08 22:40:39]

It's kind of weird to have both an INVALID and a NULL.  Maybe these could be
renamed like this?

LAST_USED_UNSET = 0;
LAST_USED_INVALID = -1

     static final long INVALID_LAST_USED = -1;
+    static final String INVALID_ORIGIN_URL = "";
 
     private static Factory sFactory = new Factory();
 
@@ -47,13 +53,9 @@ public class WebappDataStorage {
         new AsyncTask<Void, Void, Void>() {
             @Override
             protected final Void doInBackground(Void... nothing) {
-                if (storage.getLastUsedTime() == INVALID_LAST_USED) {
-                    // If the last used time is invalid then assert that there is no data
-                    // in the WebappDataStorage which needs to be cleaned up.
-                    assert storage.getAllData().isEmpty();
-                } else {
-                    storage.updateLastUsedTime();
-                }
+                // The last used time may be invalid if the user has cleared their history.
+                // The next time the webapp is opened, set it to a valid value again.
+                storage.updateLastUsedTime(System.currentTimeMillis());
                 return null;
             }
         }.execute();
@@ -86,6 +88,47 @@ public class WebappDataStorage {
     }
 
     /**
+     * Asynchronously retrieves the origin URL stored in this WebappDataStorage.
+     * @param context  The context to read the SharedPreferences file.
+     * @param webappId The ID of the web app the used time is being read for.
+     * @param callback Called when the origin has been retrieved.
+     */
+    public static void getOriginUrl(final Context context, final String webappId,
+            final FetchCallback<String> callback) {
+        new AsyncTask<Void, Void, String>() {
+            @Override
+            protected final String doInBackground(Void... nothing) {
+                String originUrl = new WebappDataStorage(context.getApplicationContext(), webappId)
+                        .getOriginUrl();
+                return originUrl;
+            }
+
+            @Override
+            protected final void onPostExecute(String originUrl) {
+                callback.onDataRetrieved(originUrl);
+            }
+        }.execute();
+    }
+
+    /**
+     * Asynchronously updates the origin URL stored in this WebappDataStorage.
+     * @param context  The context to read the SharedPreferences file.
+     * @param webappId The ID of the web app the used time is being read for.
+     * @param origin The origin to set for the web app.
+     */
+    public static void updateOriginUrl(final Context context, final String webappId,
+            final String originUrl) {
+        new AsyncTask<Void, Void, Void>() {
+            @Override
+            protected final Void doInBackground(Void... nothing) {
+                new WebappDataStorage(context.getApplicationContext(), webappId)
+                        .updateOriginUrl(originUrl);
+                return null;
+            }
+        }.execute();
+    }
+
+    /**
      * Deletes the data for a web app by clearing all the information inside the SharedPreferences
      * file. This does NOT delete the file itself but the file is left empty.
      * @param context  The context to read the SharedPreferences file.
@@ -97,6 +140,21 @@ public class WebappDataStorage {
     }
 
     /**
+     * Deletes the origin URL and sets last used time to 0 this web app in SharedPreferences.
+     * This does not remove the stored splash screen image (if any) for the app.
+     * @param context  The context to read the SharedPreferences file.
+     * @param webappId The ID of the web app being deleted.
+     */
+    static void clearHistory(final Context context, final String webappId) {
+        // The last used time is set to 0 to ensure that a valid value is always present.
+        // If the webapp is not launched prior to the next cleanup, then its remaining data will be
+        // removed. Otherwise, the next launch will update the last used time.
+        assert !ThreadUtils.runningOnUiThread();
+        openSharedPreferences(context, webappId)
+            .edit().putLong(KEY_LAST_USED, NULL_LAST_USED).remove(KEY_ORIGIN_URL).apply();

[gone, 2016/03/08 22:40:39]

nit: indent by 8

+    }
+
+    /**
      * Sets the factory used to generate WebappDataStorage objects.
      */
     @VisibleForTesting
@@ -131,9 +189,19 @@ public class WebappDataStorage {
         new UpdateTask(splashScreenImage).execute();
     }
 
-    void updateLastUsedTime() {
+    void updateOriginUrl(String originUrl) {
+        assert !ThreadUtils.runningOnUiThread();
+        mPreferences.edit().putString(KEY_ORIGIN_URL, originUrl).apply();
+    }
+
+    String getOriginUrl() {
+        assert !ThreadUtils.runningOnUiThread();
+        return mPreferences.getString(KEY_ORIGIN_URL, INVALID_ORIGIN_URL);
+    }
+
+    void updateLastUsedTime(long lastUsedTime) {
         assert !ThreadUtils.runningOnUiThread();
-        mPreferences.edit().putLong(KEY_LAST_USED, System.currentTimeMillis()).apply();
+        mPreferences.edit().putLong(KEY_LAST_USED, lastUsedTime).apply();
     }
 
     long getLastUsedTime() {
@@ -204,4 +272,4 @@ public class WebappDataStorage {
             return null;
         }
     }
-}
+}