Don't pass TabModelSelector to clients when null

If we fail to create a TabModel because there are already too many,
don't set TabModel on various clients. Rather, #finish() and return
immediately.

BUG=1059989

Change-Id: I01dca310d50de4f6665ccd23102316bc234ce611
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2097235Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Theresa  <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748922}

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

@@ -589,9 +589,6 @@ public abstract class ChromeActivity<C extends ChromeActivityComponent>
         if (mTabModelsInitialized) return;
 
         mTabModelSelector = createTabModelSelector();
-        mTabModelSelectorSupplier.set(mTabModelSelector);
-        mActivityTabProvider.setTabModelSelector(mTabModelSelector);
-        getStatusBarColorController().setTabModelSelector(mTabModelSelector);
 
         if (mTabModelSelector == null) {
             assert isFinishing();
@@ -599,6 +596,10 @@ public abstract class ChromeActivity<C extends ChromeActivityComponent>
             return;
         }
 
+        mTabModelSelectorSupplier.set(mTabModelSelector);
+        mActivityTabProvider.setTabModelSelector(mTabModelSelector);
+        getStatusBarColorController().setTabModelSelector(mTabModelSelector);
+
         Pair<? extends TabCreator, ? extends TabCreator> tabCreators = createTabCreators();
         mRegularTabCreator = tabCreators.first;
         mIncognitoTabCreator = tabCreators.second;