weblayer: Add missing return

Change-Id: I975b7d0bbd7bc7c002954939563d5e54cdcbc1f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2227375Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774423}

weblayer/browser/tab_impl.cc

@@ -618,6 +618,7 @@ void TabImpl::CaptureScreenShot(
     Java_TabImpl_runCaptureScreenShotCallback(
         env, ScopedJavaLocalRef<jobject>(value_callback),
         ScopedJavaLocalRef<jobject>(), static_cast<int>(error));
+    return;
   }
 
   rwhv->CopyFromSurface(