[ios] Active web state observer in tab collection.

ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm

Index: ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm
diff --git a/ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm b/ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm
index 1688f3e23198bdb309d0bba64a715e793a6ab7a0..8478ce5c7c9b4dc4281e6f42c1894128554e3984 100644
--- a/ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm
+++ b/ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.mm
@@ -5,6 +5,7 @@
 #import "ios/clean/chrome/browser/ui/tab_strip/tab_strip_coordinator.h"
 
 #import "ios/chrome/browser/web_state_list/web_state_list.h"
+#import "ios/clean/chrome/browser/ui/commands/tab_grid_commands.h"
 #import "ios/clean/chrome/browser/ui/commands/tab_strip_commands.h"
 #import "ios/clean/chrome/browser/ui/tab_collection/tab_collection_mediator.h"
 #import "ios/clean/chrome/browser/ui/tab_strip/tab_strip_view_controller.h"
@@ -64,6 +65,9 @@
 
 - (void)closeTabStripTabAtIndex:(int)index {
   self.webStateList.CloseWebStateAt(index);
+  if (self.webStateList.empty()) {
+    [static_cast<id<TabGridCommands>>(self.browser->dispatcher()) showTabGrid];
+  }
 }
 
 @end