Implement server-suggested update check backoff

chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java

Index: chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java
diff --git a/chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java b/chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java
index 3148d26f855dfda65c034995f8052e0f5cf2a742..508c0d6e59cc9a2ccb87b916aca46d5273e4c334 100644
--- a/chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java
+++ b/chrome/android/junit/src/org/chromium/chrome/browser/webapps/WebApkUpdateManagerTest.java
@@ -410,6 +410,30 @@ public class WebApkUpdateManagerTest {
     }
 
     /**
+     * Test that if a WebAPK is expected to check update less frequently, the is-update-needed

[pkotwicz, 2017/02/14 00:15:13]

Nit: "update" -> "updates"

[Xi Han, 2017/02/14 22:25:46]

Done.

+     * check is done after an extended time interval (as opposed to the usual delay).
+     */
+    @Test
+    public void testInfrequentUpdateIntervalIfNoPriorWebApkUpdate() {
+        assertTrue(WebApkUpdateManager.INFREQUENT_UPDATE_INTERVAL
+                > WebApkUpdateManager.FULL_CHECK_UPDATE_INTERVAL);
+
+        getStorage().delete();

[pkotwicz, 2017/02/14 00:15:12]

Why do you delete the storage?

[Xi Han, 2017/02/14 22:25:46]

Reverted.

+        WebappDataStorage storage = getStorage();
+
+        // Done when WebAPK is registered in {@link WebApkActivity}.
+        storage.updateTimeOfLastCheckForUpdatedWebManifest();
+        storage.updateInfrequentUpdates(true);
+
+        assertFalse(updateIfNeededChecksForUpdatedWebManifest());
+        mClock.advance(WebApkUpdateManager.FULL_CHECK_UPDATE_INTERVAL);
+        assertFalse(updateIfNeededChecksForUpdatedWebManifest());
+        mClock.advance(WebApkUpdateManager.INFREQUENT_UPDATE_INTERVAL
+                - WebApkUpdateManager.FULL_CHECK_UPDATE_INTERVAL);
+        assertTrue(updateIfNeededChecksForUpdatedWebManifest());
+    }
+
+    /**
      * Test that the is-update-needed check is tried the next time that the WebAPK is launched if
      * Chrome is killed prior to the initial URL finishing loading.
      */