Check fullscreen manager before setting control state

The fullscreen manager can be null in cases where a different
activity is showing. This CL adds a check to make sure it is there
before using it.

BUG=672730, 670459

Review-Url: https://codereview.chromium.org/2557403004
Cr-Commit-Position: refs/heads/master@{#437578}

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManager.java

@@ -256,8 +256,10 @@ public abstract class LayoutManager implements LayoutUpdateHost, LayoutProvider,
             TabContentManager tabContentManager, ResourceManager resourceManager,
             ChromeFullscreenManager fullscreenManager) {
         // Update the android browser controls state.
-        fullscreenManager.setHideBrowserControlsAndroidView(
-                mActiveLayout.forceHideBrowserControlsAndroidView());
+        if (fullscreenManager != null) {
+            fullscreenManager.setHideBrowserControlsAndroidView(
+                    mActiveLayout.forceHideBrowserControlsAndroidView());
+        }
 
         getViewportPixel(mCachedVisibleViewport);
         mHost.getWindowViewport(mCachedWindowViewport);