Update ChromeWebContentsHandler to check Browser creation possibility.

ChromeWebContentsHandler::OpenURLFromTab can request Browser creation
when that is not possible, and assume it's done.
This is now handled by returning NULL when Browser can not be created.

Bug: 1162795
Change-Id: I522c7754184fc47fedc202f25cb7311c33880372
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2609131
Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#849209}

chrome/browser/ui/webui/chrome_web_contents_handler.cc

@@ -35,13 +35,17 @@ WebContents* ChromeWebContentsHandler::OpenURLFromTab(
     WebContents* source,
     const OpenURLParams& params) {
   if (!context)
-    return NULL;
+    return nullptr;
 
   Profile* profile = Profile::FromBrowserContext(context);
 
   Browser* browser = chrome::FindTabbedBrowser(profile, false);
   const bool browser_created = !browser;
   if (!browser) {
+    if (Browser::GetCreationStatusForProfile(profile) !=
+        Browser::CreationStatus::kOk) {
+      return nullptr;
+    }
     // TODO(erg): OpenURLParams should pass a user_gesture flag, pass it to
     // CreateParams, and pass the real value to nav_params below.
     browser = Browser::Create(