Add assertion for tab.isInitialized()

To assist in the investigation of how uninitialized
Tabs are appearing in getDomain()

Bug: 1116613
Change-Id: Ia0ab0d7aca20d724fd1200b1fdbe1a2f951f9633
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363485
Commit-Queue: David Maunder <davidjm@chromium.org>
Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799482}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediator.java

@@ -1336,6 +1336,7 @@ class TabListMediator {
     protected static String getDomain(Tab tab) {
         // TODO(crbug.com/1116613) Investigate how uninitialized Tabs are appearing
         // here.
+        assert tab.isInitialized();
         if (!tab.isInitialized()) {
             return "";
         }

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediatorUnitTest.java

@@ -2190,11 +2190,11 @@ public class TabListMediatorUnitTest {
         mCallbackCaptor.getValue().onResult(mFaviconDrawable);
     }
 
-    @Test
+    @Test(expected = AssertionError.class)
     public void testGetDomainOnDestroyedTab() {
         Tab tab = new MockTab(TAB1_ID, false);
         tab.destroy();
-        assertEquals("", TabListMediator.getDomain(tab));
+        TabListMediator.getDomain(tab);
     }
 
     private void initAndAssertAllProperties() {