Report redirect UMA in offline interceptor

chrome/browser/android/offline_pages/offline_page_request_job_unittest.cc

 // Copyright 2016 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 "chrome/browser/android/offline_pages/offline_page_request_job.h"
 
 #include "base/callback.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/memory/ptr_util.h"
@@ skipping 231 matching lines @@
                 const ClientId& client_id,
                 const GURL& original_url,
                 std::unique_ptr<OfflinePageArchiver> archiver);
 
   void InterceptRequest(const GURL& url,
                         const std::string& method,
                         const std::string& extra_header_name,
                         const std::string& extra_header_value,
                         content::ResourceType resource_type);
 
+  // Expect one count of|result| UMA reported and no more.

[fgorski, 2016/11/18 23:52:22]

nit: space before |

Expect exactly one...  drop " and no more."

First explain what "and no more" means. I s it opposite of explanation in 258?
In that case capture it more explicitly. 

[jianli, 2016/11/19 00:54:05]

Done.
Yes.

   void ExpectAggregatedRequestResultHistogram(
       OfflinePageRequestJob::AggregatedRequestResult result);
+  // Expect multiple |count| of |result| UMA reported and no more.

[fgorski, 2016/11/18 23:52:22]

Expect exactly |count|... and drop "and no more"

[jianli, 2016/11/19 00:54:05]

Done.

   void ExpectAggregatedRequestResultHistogramWithCount(
       OfflinePageRequestJob::AggregatedRequestResult result, int count);
+  // Expect one count of |result| UMA reported. Some other UMAs might also be
+  // reported.
+  void ExpectAggregatedRequestResultHistogramOnMultiBuckets(

[fgorski, 2016/11/18 23:52:22]

This is meant to be exactly one in specific bucket, and ignore other buckets?
Probably we could rename that to.

[jianli, 2016/11/19 00:54:05]

Eexactly one in specific bucket and other buckets could also have data.

+      OfflinePageRequestJob::AggregatedRequestResult result);
 
   net::TestURLRequestContext* url_request_context() {
     return test_url_request_context_.get();
   }
   Profile* profile() { return profile_; }
   OfflinePageTabHelper* offline_page_tab_helper() const {
     return offline_page_tab_helper_;
   }
   int64_t offline_id() const { return offline_id_; }
   int64_t offline_id2() const { return offline_id2_; }
@@ skipping 186 matching lines @@
   histogram_tester_.ExpectUniqueSample(
       kAggregatedRequestResultHistogram, static_cast<int>(result), 1);
 }
 
 void OfflinePageRequestJobTest::ExpectAggregatedRequestResultHistogramWithCount(
     OfflinePageRequestJob::AggregatedRequestResult result, int count) {
   histogram_tester_.ExpectUniqueSample(
       kAggregatedRequestResultHistogram, static_cast<int>(result), count);
 }
 
+void
+OfflinePageRequestJobTest::ExpectAggregatedRequestResultHistogramOnMultiBuckets(
+    OfflinePageRequestJob::AggregatedRequestResult result) {
+  histogram_tester_.ExpectBucketCount(
+      kAggregatedRequestResultHistogram, static_cast<int>(result), 1);
+}
+
 void OfflinePageRequestJobTest::SavePage(
     const GURL& url,
     const ClientId& client_id,
     const GURL& original_url,
     std::unique_ptr<OfflinePageArchiver> archiver) {
   OfflinePageModel::SavePageParams save_page_params;
   save_page_params.url = url;
   save_page_params.client_id = client_id;
   save_page_params.original_url = original_url;
   OfflinePageModelFactory::GetForBrowserContext(profile())->SavePage(
@@ skipping 361 matching lines @@
 
   // This should trigger redirect first.
   InterceptRequest(
       kTestOriginalUrl, "GET", "", "", content::RESOURCE_TYPE_MAIN_FRAME);
   base::RunLoop().Run();
 
   EXPECT_EQ(kTestFileSize3, bytes_read());
   ASSERT_TRUE(offline_page_tab_helper()->GetOfflinePageForTest());
   EXPECT_EQ(offline_id3(),
             offline_page_tab_helper()->GetOfflinePageForTest()->offline_id);
-  ExpectAggregatedRequestResultHistogram(
+  ExpectAggregatedRequestResultHistogramOnMultiBuckets(
+      OfflinePageRequestJob::AggregatedRequestResult::
+          REDIRECTED_ON_DISCONNECTED_NETWORK);
+  ExpectAggregatedRequestResultHistogramOnMultiBuckets(
       OfflinePageRequestJob::AggregatedRequestResult::
           SHOW_OFFLINE_ON_DISCONNECTED_NETWORK);
 }
 
 }  // namespace offline_pages