Add calls to the server to request WebAPK updates.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkInstaller.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkInstaller.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkInstaller.java
index e41e461cd3ea400b3a8b53d983d7944c5d7b64cd..1bbf42a4e68a252c21baf61d0042326e46762ceb 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkInstaller.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebApkInstaller.java
@@ -18,7 +18,7 @@ import java.io.File;
 
 /**
  * Java counterpart to webapk_installer.h
- * Contains functionality to install WebAPKs.
+ * Contains functionality to install / update WebAPKs.
  */
 public class WebApkInstaller {
     private static final String TAG = "WebApkInstaller";
@@ -50,6 +50,18 @@ public class WebApkInstaller {
     }
 
     /**
+     * Updates a WebAPK.
+     * @param filePath File to update.
+     * @param packageName Package name to update WebAPK at.
+     * @return True if the update was started. A "true" return value does not guarantee that the
+     *         update succeeds.
+     */
+    @CalledByNative
+    private static boolean updateAsyncFromNative(String filePath, String packageName) {
+        return false;
+    }
+
+    /**
      * Returns whether the user has enabled installing apps from sources other than the Google Play
      * Store.
      */