Android: Fix a crash in BrowserControlsManager

Checks if the curren Tab is in destroyed state in order to
prevent BrowserControlsManager from accessing
TabBrowserControlsConstraintsHelper after the tab becomes
invalid.

Bug: 1110909
Change-Id: Ib6cccfdf61abcc18f1f0f5300bc80901c696cef9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2418274Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809253}

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/BrowserControlsManager.java

@@ -504,7 +504,7 @@ public class BrowserControlsManager
      */
     private void setPositionsForTabToNonFullscreen() {
         Tab tab = getTab();
-        if (tab == null
+        if (tab == null || !tab.isInitialized()
                 || TabBrowserControlsConstraintsHelper.getConstraints(tab)
                         != BrowserControlsState.HIDDEN) {
             setPositionsForTab(0, 0, getTopControlsHeight(), getTopControlsMinHeight(),