[TabViewManager] Fix omnibox focus issue

This makes all Views added through TabViewManager explicitly focusable.

On some versions of Android, these views were not focusable by default
and this led to an issue where the omnibox gained focus after a View
was added and it never releases the focus.

Bug: 1081628
Change-Id: Ifb272500a274dfd64f432650a567ce20881e6c50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2307536Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Mehran Mahmoudi <mahmoudi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790062}

chrome/android/java/src/org/chromium/chrome/browser/tab/TabViewManagerImpl.java

@@ -122,6 +122,8 @@ class TabViewManagerImpl implements TabViewManager, Comparator<TabViewProvider>
             if (currentTabViewProvider != null) {
                 view = currentTabViewProvider.getView();
                 assert view != null;
+                view.setFocusable(true);
+                view.setFocusableInTouchMode(true);
             }
             mCurrentView = view;
             initMarginSupplier();