[iOS] Upstream some stability code

ios/chrome/browser/crash_report/crash_report_user_application_state.mm

Index: ios/chrome/browser/crash_report/crash_report_user_application_state.mm
diff --git a/ios/chrome/browser/crash_report/crash_report_user_application_state.mm b/ios/chrome/browser/crash_report/crash_report_user_application_state.mm
new file mode 100644
index 0000000000000000000000000000000000000000..4182d583e5b2807fdd11a0343101bdba36abd214
--- /dev/null
+++ b/ios/chrome/browser/crash_report/crash_report_user_application_state.mm
@@ -0,0 +1,24 @@
+// 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.
+
+#import "ios/chrome/browser/crash_report/crash_report_user_application_state.h"
+
+namespace {
+NSString* const kBrowserState = @"user_application_state";
+}
+
+@implementation CrashReportUserApplicationState
+
++ (CrashReportUserApplicationState*)sharedInstance {
+  static CrashReportUserApplicationState* instance =
+      [[CrashReportUserApplicationState alloc] init];
+  return instance;
+}
+
+- (id)init {
+  self = [super initWithKey:kBrowserState];
+  return self;
+}
+
+@end