Move testEvictedTabReloadFailure to an external URL egtest target.

ios/chrome/browser/metrics/external_url_tab_usage_recorder_egtest.mm

Index: ios/chrome/browser/metrics/external_url_tab_usage_recorder_egtest.mm
diff --git a/ios/chrome/browser/metrics/external_url_tab_usage_recorder_egtest.mm b/ios/chrome/browser/metrics/external_url_tab_usage_recorder_egtest.mm
new file mode 100644
index 0000000000000000000000000000000000000000..5075d1414dd881b3d67ab8c1474875d6f4092c43
--- /dev/null
+++ b/ios/chrome/browser/metrics/external_url_tab_usage_recorder_egtest.mm
@@ -0,0 +1,61 @@
+// Copyright 2017 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 <EarlGrey/EarlGrey.h>
+
+#import "ios/chrome/browser/metrics/tab_usage_recorder.h"
+#import "ios/chrome/browser/metrics/tab_usage_recorder_test_util.h"
+#import "ios/chrome/test/app/histogram_test_util.h"
+#import "ios/chrome/test/app/tab_test_util.h"
+#import "ios/chrome/test/earl_grey/chrome_earl_grey.h"
+#import "ios/chrome/test/earl_grey/chrome_test_case.h"
+#include "ios/web/public/test/http_server_util.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace {
+
+const char kTestUrl[] =
+    "http://ios/testing/data/http_server_files/memory_usage.html";
+
+}  // namespace
+
+// Test for the TabUsageRecorder class.

[baxley, 2017/05/01 23:20:06]

Update comment to mention external URL tests for TabUsageRecorder?

[lpromero, 2017/05/02 13:56:01]

Done.

+@interface ExternalURLTabUsageRecorderTestCase : ChromeTestCase
+@end
+
+@implementation ExternalURLTabUsageRecorderTestCase
+
+// Verify correct recording of metrics when the reloading of an evicted tab
+// fails.
+- (void)testEvictedTabReloadFailure {
+  web::test::SetUpFileBasedHttpServer();
+  chrome_test_util::HistogramTester histogramTester;
+  FailureBlock failureBlock = ^(NSString* error) {
+    GREYFail(error);
+  };
+
+  // This URL is purposely invalid so it triggers a navigation error.
+  GURL invalidURL(kTestUrl);
+
+  chrome_test_util::OpenNewTab();
+  [ChromeEarlGrey loadURL:invalidURL];
+  [ChromeEarlGrey waitForErrorPage];
+  tab_usage_recorder_test_util::OpenNewIncognitoTabUsingUIAndEvictMainTabs();
+
+  tab_usage_recorder_test_util::SwitchToNormalMode();
+  [ChromeEarlGrey waitForErrorPage];
+
+  histogramTester.ExpectUniqueSample(kEvictedTabReloadSuccessRate,
+                                     TabUsageRecorder::LOAD_FAILURE, 1,
+                                     failureBlock);
+  histogramTester.ExpectUniqueSample(kDidUserWaitForEvictedTabReload,
+                                     TabUsageRecorder::USER_WAITED, 1,
+                                     failureBlock);
+  histogramTester.ExpectTotalCount(kEvictedTabReloadTime, 0, failureBlock);
+}
+
+@end