Enable deep-linking from notifications for recently used web apps on the Android home screen.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.webapps;
 
 import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.graphics.Bitmap;
 import android.os.AsyncTask;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.ShortcutHelper;
 import org.chromium.chrome.browser.ShortcutSource;
 import org.chromium.chrome.browser.util.IntentUtils;
 import org.chromium.content_public.common.ScreenOrientationValues;
 
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Stores data about an installed web app. Uses SharedPreferences to persist the data to disk.
  * This class must only be accessed via {@link WebappRegistry}, which is used to register and keep
  * track of web app data known to Chrome.
  */
 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_URL = "url";
     static final String KEY_SCOPE = "scope";
     static final String KEY_ICON = "icon";
     static final String KEY_NAME = "name";
     static final String KEY_SHORT_NAME = "short_name";
     static final String KEY_ORIENTATION = "orientation";
     static final String KEY_THEME_COLOR = "theme_color";
     static final String KEY_BACKGROUND_COLOR = "background_color";
     static final String KEY_SOURCE = "source";
     static final String KEY_ACTION = "action";
     static final String KEY_IS_ICON_GENERATED = "is_icon_generated";
     static final String KEY_VERSION = "version";
+    static final String KEY_LAUNCHED = "launched";
 
     // Unset/invalid constants for last used times and URLs. 0 is used as the null last
     // used time as WebappRegistry assumes that this is always a valid timestamp.
     static final long LAST_USED_UNSET = 0;
     static final long LAST_USED_INVALID = -1;
     static final String URL_INVALID = "";
     static final int VERSION_INVALID = 0;
 
+    // We use a heuristic to determine whether a web app is still installed on the homescreen, as
+    // there is no way to do so directly. Any web app which has been opened in the last ten days
+    // is considered to be still on the homescreen.
+    static final long WEBAPP_LAST_OPEN_MAX_TIME = TimeUnit.DAYS.toMillis(10L);
+
+    private static Clock sClock = new Clock();
     private static Factory sFactory = new Factory();
 
     private final String mId;
     private final SharedPreferences mPreferences;
 
     /**
      * Opens an instance of WebappDataStorage for the web app specified. Must not be run on the UI
      * thread.
      * @param context  The context to open the SharedPreferences.
      * @param webappId The ID of the web app which is being opened.
@@ skipping 59 matching lines @@
         }.execute();
     }
 
     /**
      * Asynchronously retrieves the URL stored in this WebappDataStorage. Used in testing.
      * @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 URL has been retrieved.
      */
     @VisibleForTesting
-    public static void getURL(final Context context, final String webappId,
+    public static void getUrl(final Context context, final String webappId,
             final FetchCallback<String> callback) {
         new AsyncTask<Void, Void, String>() {
             @Override
             protected final String doInBackground(Void... nothing) {
-                return new WebappDataStorage(context.getApplicationContext(), webappId).getURL();
+                return new WebappDataStorage(context.getApplicationContext(), webappId).getUrl();
             }
 
             @Override
             protected final void onPostExecute(String url) {
                 assert callback != null;
                 callback.onDataRetrieved(url);
             }
         }.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.
      * @param webappId The ID of the web app being deleted.
      */
     static void deleteDataForWebapp(final Context context, final String webappId) {
         assert !ThreadUtils.runningOnUiThread();
         openSharedPreferences(context, webappId).edit().clear().apply();
     }
 
     /**
-     * Deletes the URL and scope, and sets last used time to 0 in SharedPreferences.
+     * Deletes the launched flag, URL and scope, and sets last used time to 0 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 for which history is being cleared.
      */
     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 web app 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.
+        // removed. Otherwise, the next launch from homescreen will update the last used time.

[gone, 2016/04/07 19:10:44]

home screen, here and everywhere else

[dominickn, 2016/04/08 01:10:45]

Done.

         assert !ThreadUtils.runningOnUiThread();
-        openSharedPreferences(context, webappId).edit()
-                .putLong(KEY_LAST_USED, LAST_USED_UNSET).remove(KEY_URL).remove(KEY_SCOPE).apply();
+        openSharedPreferences(context, webappId).edit().putLong(KEY_LAST_USED, LAST_USED_UNSET)

[gone, 2016/04/07 19:10:44]

At this point, should the sharedPreferences just be stored temporarily and then
each of the removals or changes should be put into their own lines?  It's kind
of weird to parse.

[dominickn, 2016/04/08 01:10:45]

Done.

+                .remove(KEY_LAUNCHED).remove(KEY_URL).remove(KEY_SCOPE).apply();
     }
 
     /**
+     * Sets the clock used to get the current time.
+     */
+    @VisibleForTesting
+    public static void setClockForTests(Clock clock) {
+        sClock = clock;
+    }
+
+    /**
      * Sets the factory used to generate WebappDataStorage objects.
      */
     @VisibleForTesting
     public static void setFactoryForTests(Factory factory) {
         sFactory = factory;
     }
 
     private static SharedPreferences openSharedPreferences(Context context, String webappId) {
         return context.getApplicationContext().getSharedPreferences(
                 SHARED_PREFS_FILE_PREFIX + webappId, Context.MODE_PRIVATE);
@@ skipping 135 matching lines @@
     /**
      * Returns the scope stored in this object, or URL_INVALID if it is not stored.
      */
     String getScope() {
         return mPreferences.getString(KEY_SCOPE, URL_INVALID);
     }
 
     /**
      * Returns the URL stored in this object, or URL_INVALID if it is not stored.
      */
-    String getURL() {
+    String getUrl() {
         return mPreferences.getString(KEY_URL, URL_INVALID);
     }
 
     /**
      * Updates the last used time of this object.
-     * @param lastUsedTime the new last used time.
      */
     void updateLastUsedTime() {
-        mPreferences.edit().putLong(KEY_LAST_USED, System.currentTimeMillis()).apply();
+        mPreferences.edit().putLong(KEY_LAST_USED, sClock.currentTimeMillis()).apply();
     }
 
     /**
      * Returns the last used time of this object, or -1 if it is not stored.
      */
     long getLastUsedTime() {
         return mPreferences.getLong(KEY_LAST_USED, LAST_USED_INVALID);
     }
 
+    /**
+     * Returns true if this web app has been launched from homescreen recently (within 10 days).

[gone, 2016/04/07 19:10:44]

This seems like a comment that'll go out of sync quickly.  Maybe refer to
WEBAPP_LAST_OPEN_MAX_TIME instead?

[dominickn, 2016/04/08 01:10:45]

Done.

+     */
+    public boolean wasLaunchedRecently() {
+        // Registering the web app sets the last used time, so we must also ensure that the web app
+        // has actually been launched. Otherwise, launches from homescreen are the only occasion
+        // when last used time is updated.
+        return getLaunched()
+                && (sClock.currentTimeMillis() - getLastUsedTime() < WEBAPP_LAST_OPEN_MAX_TIME);
+    }
+
+    /**
+     * Returns true if this web app has been launched from homescreen.
+     */
+    boolean getLaunched() {
+        return mPreferences.getBoolean(KEY_LAUNCHED, false);
+    }
+
+    /**
+     * Marks this web app as having been launched from homescreen.
+     */
+    void setLaunched() {
+        mPreferences.edit().putBoolean(KEY_LAUNCHED, true).apply();
+    }
+
     private Map<String, ?> getAllData() {
         return mPreferences.getAll();
     }
 
     /**
      * Called after data has been retrieved from storage.
      */
     public interface FetchCallback<T> {
         public void onDataRetrieved(T readObject);
     }
 
     /**
      * Factory used to generate WebappDataStorage objects.
      *
      * It is used in tests to override methods in WebappDataStorage and inject the mocked objects.
      */
     public static class Factory {
 
         /**
          * Generates a WebappDataStorage class for a specified web app.
          */
         public WebappDataStorage create(final Context context, final String webappId) {
             return new WebappDataStorage(context, webappId);
         }
     }
+
+    /**
+     * Clock used to generate the current time in millseconds for updating and setting last used
+     * time.
+     */
+    public static class Clock {
+        /**
+         * Returns the current time in milliseconds.
+         */
+        public long currentTimeMillis() {
+            return System.currentTimeMillis();
+        }
+    }
 }