Add a variations parameter to control WebAPK renderer launching.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/ChromeWebApkHost.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ChromeWebApkHost.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ChromeWebApkHost.java
index caeddde96365078166cee906790e02937fa473cd..5cff215571b25f7808af69c15a5542cdff8892a7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ChromeWebApkHost.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ChromeWebApkHost.java
@@ -113,6 +113,13 @@ public class ChromeWebApkHost {
     }
 
     /**
+     * Returns whether WebAPK renderer process is enabled by Chrome.
+     */
+    public static boolean canLaunchWebApkRenderer() {
+        return isEnabled() && LibraryLoader.isInitialized() && nativeCanLaunchWebApkRenderer();
+    }
+
+    /**
      * Returns whether installing WebAPKs is possible either from "unknown resources" or Google
      * Play.
      */
@@ -168,5 +175,6 @@ public class ChromeWebApkHost {
     }
 
     private static native boolean nativeCanUseGooglePlayToInstallWebApk();
+    private static native boolean nativeCanLaunchWebApkRenderer();
     private static native boolean nativeCanInstallFromUnknownSources();
 }