Fix crash in FeedStreamSurface

Bug: 1116919
Change-Id: I96bd5bd3e69433639550d997847d6a2bf0540744
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360231
Auto-Submit: Dan H <harringtond@chromium.org>
Reviewed-by: Ian Wells <iwells@chromium.org>
Commit-Queue: Ian Wells <iwells@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798670}

chrome/android/feed/core/java/src/org/chromium/chrome/browser/feed/v2/FeedStreamSurface.java

@@ -174,6 +174,8 @@ public class FeedStreamSurface implements SurfaceActionsHandler, FeedActionsHand
      *  Clear all the data related to all surfaces.
      */
     public static void clearAll() {
+        if (sSurfaces == null) return;
+
         ArrayList<FeedStreamSurface> openSurfaces = new ArrayList<FeedStreamSurface>();
         for (FeedStreamSurface surface : sSurfaces) {
             if (surface.isOpened()) openSurfaces.add(surface);