Introduce ManifestUpgradeDetector for WebAPK to detect web manifest changes.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
index b369549608351605ca3200f4d26a2d3d29b87473..7c4a070defd51917c2f13376bbf5e96ed1f2895e 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkActivity.java
@@ -27,6 +27,9 @@ import org.chromium.webapk.lib.client.WebApkServiceConnectionManager;
  * UI-less Chrome.
  */
 public class WebApkActivity extends WebappActivity {
+    /** Detects whether the associated Web Manifest changes. */
+    private ManifestUpgradeDetector mManifestUpgradeDetector = null;
+
     @Override
     protected void onNewIntent(Intent intent) {
         super.onNewIntent(intent);
@@ -143,6 +146,18 @@ public class WebApkActivity extends WebappActivity {
     }
 
     @Override
+    public void finishNativeInitialization() {
+        super.finishNativeInitialization();
+
+        // TODO(hanxi): Ask WebApk's update manager whether to check resource updates.
+        if (mManifestUpgradeDetector == null) {
+            mManifestUpgradeDetector =
+                    new ManifestUpgradeDetector(getActivityTab(), mWebappInfo);
+        }
+        mManifestUpgradeDetector.start();
+    }
+
+    @Override
     public void onPause() {
         super.onPause();
         initializeChildProcessCreationParams(false);
@@ -164,4 +179,12 @@ public class WebApkActivity extends WebappActivity {
         }
         ChildProcessCreationParams.set(params);
     }
+
+    @Override
+    protected void onDestroyInternal() {
+        if (mManifestUpgradeDetector != null) {
+            mManifestUpgradeDetector.destroy();
+        }
+        super.onDestroyInternal();
+    }
 }