Fix ios_chrome_unittests to crash on DCHECK failure.

ios/chrome/browser/crash_loop_detection_util_unittest.mm

 // Copyright 2013 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 <Foundation/Foundation.h>
 
 #include "ios/chrome/browser/crash_loop_detection_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 namespace {
 // The key used to store the count in the implementation.
 NSString* const kAppStartupAttemptCountKey = @"AppStartupFailureCount";
 
 typedef PlatformTest CrashLoopDetectionUtilTest;
 
 TEST_F(CrashLoopDetectionUtilTest, FullCycle) {
+  crash_util::ResetFailedStartupAttemptCountForTests();
+
   // Simulate one prior crash.
   NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
   [defaults setInteger:1 forKey:kAppStartupAttemptCountKey];
 
   EXPECT_EQ(1, crash_util::GetFailedStartupAttemptCount());
 
   crash_util::IncrementFailedStartupAttemptCount(false);
 
   // It should still report 1, since it's reporting failures prior to this
   // launch.
   EXPECT_EQ(1, crash_util::GetFailedStartupAttemptCount());
   // ... but under the hood the value should now be 2.
   EXPECT_EQ(2, [defaults integerForKey:kAppStartupAttemptCountKey]);
 
   // If it's mistakenly incerement again, nothing should change.
   crash_util::IncrementFailedStartupAttemptCount(false);
   EXPECT_EQ(2, [defaults integerForKey:kAppStartupAttemptCountKey]);
 
   // After a reset it should be 0 internally, but the same via the API.
   crash_util::ResetFailedStartupAttemptCount();
   EXPECT_EQ(1, crash_util::GetFailedStartupAttemptCount());
   EXPECT_EQ(0, [defaults integerForKey:kAppStartupAttemptCountKey]);
 }
 
 }  // namespace