Add an about:flag to control WebApk enablement.

chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java b/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
index 936279dd595f5887c23ef20d07d17be46255304f..ee11aedb50cafc998e8f72efbd7cf73fb82288d9 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ShortcutHelper.java
@@ -26,13 +26,14 @@ import android.text.TextUtils;
 import android.util.Base64;
 
 import org.chromium.base.ApiCompatibilityUtils;
-import org.chromium.base.CommandLine;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.chrome.R;
+import org.chromium.chrome.browser.webapps.ChromeWebApkHost;
+import org.chromium.chrome.browser.webapps.WebappActivity;
 import org.chromium.chrome.browser.webapps.WebappAuthenticator;
 import org.chromium.chrome.browser.webapps.WebappDataStorage;
 import org.chromium.chrome.browser.webapps.WebappLauncherActivity;
@@ -423,14 +424,19 @@ public class ShortcutHelper {
      * {@link url}.
      */
     @CalledByNative
-    public static boolean isWebApkInstalled(String url) {
-        if (!CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_WEBAPK)) {
+    private static boolean isWebApkInstalled(String url) {
+        if (!ChromeWebApkHost.isEnabled()) {
             return false;
         }
         return WebApkValidator.queryWebApkPackage(ContextUtils.getApplicationContext(), url)
                 != null;
     }
 
+    @CalledByNative
+    private static boolean areWebApksEnabled() {
+        return ChromeWebApkHost.isEnabled();
+    }
+
     /**
      * Compresses a bitmap into a PNG and converts into a Base64 encoded string.
      * The encoded string can be decoded using {@link decodeBitmapFromString(String)}.