[Android] Allow custom ActionMode creation via ContentViewClient

android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java

Index: android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java
diff --git a/android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java b/android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java
index fc88ff3acf91934031b4aca45f21e8147307963d..6d6022f9c26dc54c0518e7b79a9aeb1d666dac35 100644
--- a/android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java
+++ b/android_webview/test/shell/src/org/chromium/android_webview/test/NullContentsClient.java
@@ -25,6 +25,8 @@ import org.chromium.android_webview.JsPromptResultReceiver;
 import org.chromium.android_webview.JsResultReceiver;
 import org.chromium.android_webview.permission.AwPermissionRequest;
 import org.chromium.base.ThreadUtils;
+import org.chromium.content.browser.SelectActionMode;
+import org.chromium.content.browser.SelectActionModeCallback.ActionHandler;
 
 import java.security.Principal;
 
@@ -82,6 +84,17 @@ public class NullContentsClient extends AwContentsClient {
     }
 
     @Override
+    public SelectActionMode startActionMode(
+            View view, ActionHandler actionHandler, boolean floating) {
+        return null;
+    }
+
+    @Override
+    public boolean supportsFloatingActionMode() {
+        return false;
+    }
+
+    @Override
     public void onLoadResource(String url) {
     }