No-op when trying to evaluate null string.

content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java

Index: content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
index 48a7e1d0f0e95cb23b7e6b23a7dc9868fa9d680a..db674c15da55eb90320af133c078964d821d5221 100644
--- a/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
+++ b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsImpl.java
@@ -316,13 +316,14 @@ import java.util.UUID;
 
     @Override
     public void evaluateJavaScript(String script, JavaScriptCallback callback) {
-        if (isDestroyed()) return;
+        if (isDestroyed() || script == null) return;
         nativeEvaluateJavaScript(mNativeWebContentsAndroid, script, callback);
     }
 
     @Override
     @VisibleForTesting
     public void evaluateJavaScriptForTests(String script, JavaScriptCallback callback) {
+        if (script == null) return;
         nativeEvaluateJavaScriptForTests(mNativeWebContentsAndroid, script, callback);
     }