Fix crash when AppBannerClient is null when resolveBeforeInstallPromptPromise is called.

components/test_runner/test_runner.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/test_runner/test_runner.h"
 
 #include <stddef.h>
 #include <limits>
 #include <utility>
 
@@ skipping 2940 matching lines @@
       request_id, event_platforms,
       base::Bind(&TestRunner::DispatchBeforeInstallPromptCallback,
                  weak_factory_.GetWeakPtr(),
                  base::Passed(v8::UniquePersistent<v8::Function>(
                      blink::mainThreadIsolate(), callback))));
 }
 
 void TestRunner::ResolveBeforeInstallPromptPromise(
     int request_id,
     const std::string& platform) {
+  if (!test_interfaces_->GetAppBannerClient())
+    return;
   test_interfaces_->GetAppBannerClient()->ResolvePromise(request_id, platform);
 }
 
 void TestRunner::RunIdleTasks(v8::Local<v8::Function> callback) {
     delegate_->RunIdleTasks(
         CreateClosureThatPostsV8Callback(callback));
 }
 
 void TestRunner::SetPOSIXLocale(const std::string& locale) {
   delegate_->SetLocale(locale);
@@ skipping 278 matching lines @@
 }
 
 void TestRunner::DidLosePointerLockInternal() {
   bool was_locked = pointer_locked_;
   pointer_locked_ = false;
   if (was_locked)
     web_view_->didLosePointerLock();
 }
 
 }  // namespace test_runner