Disable close tab option when there are no open tabs.

Bug: 1155761
Change-Id: I9c98e3c0066c98e9d9fe7fad43442c0615bda4be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2576112Reviewed-by: Xi Han <hanxi@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Hao Dong <spdonghao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835085}

chrome/android/features/start_surface/internal/javatests/src/org/chromium/chrome/features/start_surface/StartSurfaceNoTabsTest.java

@@ -8,9 +8,11 @@ import static androidx.test.espresso.Espresso.onView;
 import static androidx.test.espresso.assertion.ViewAssertions.matches;
 import static androidx.test.espresso.matcher.ViewMatchers.Visibility.GONE;
 import static androidx.test.espresso.matcher.ViewMatchers.isDisplayed;
+import static androidx.test.espresso.matcher.ViewMatchers.isEnabled;
 import static androidx.test.espresso.matcher.ViewMatchers.withEffectiveVisibility;
 import static androidx.test.espresso.matcher.ViewMatchers.withId;
 
+import static org.hamcrest.Matchers.not;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -167,6 +169,7 @@ public class StartSurfaceNoTabsTest {
                 .check(matches(withEffectiveVisibility(GONE)));
         onView(withId(org.chromium.chrome.tab_ui.R.id.more_tabs))
                 .check(matches(withEffectiveVisibility(GONE)));
+        onView(withId(R.id.start_tab_switcher_button)).check(matches(not(isEnabled())));
     }
 
     @Test

chrome/android/java/src/org/chromium/chrome/browser/toolbar/TabSwitcherButtonCoordinator.java

@@ -64,6 +64,7 @@ public class TabSwitcherButtonCoordinator {
 
     public void setTabCountProvider(TabCountProvider tabCountProvider) {
         mTabCountProvider = tabCountProvider;
+        updateButtonState();
         mTabCountObserver = new TabCountObserver() {
             @Override
             public void onTabCountChanged(int tabCount, boolean isIncognito) {