Add attempt count metric to FaviconHandler

components/favicon/core/favicon_handler_unittest.cc

Index: components/favicon/core/favicon_handler_unittest.cc
diff --git a/components/favicon/core/favicon_handler_unittest.cc b/components/favicon/core/favicon_handler_unittest.cc
index 5cbe691f441020857267ecfeac8505a508e94c74..26e8c32dbf96d7eca2c7779ca4242e0d2d9b4c76 100644
--- a/components/favicon/core/favicon_handler_unittest.cc
+++ b/components/favicon/core/favicon_handler_unittest.cc
@@ -8,6 +8,7 @@
 
 #include <memory>
 #include <set>
+#include <string>
 #include <vector>
 
 #include "base/macros.h"
@@ -15,6 +16,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/strings/stringprintf.h"
+#include "base/test/histogram_tester.h"
 #include "components/favicon/core/favicon_driver.h"
 #include "components/favicon/core/test/mock_favicon_service.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -33,6 +35,7 @@ using favicon_base::FaviconRawBitmapResult;
 using favicon_base::TOUCH_ICON;
 using favicon_base::TOUCH_PRECOMPOSED_ICON;
 using testing::Assign;
+using testing::Contains;
 using testing::ElementsAre;
 using testing::InSequence;
 using testing::Invoke;
@@ -90,7 +93,7 @@ std::vector<FaviconRawBitmapResult> CreateRawBitmapResult(
   return {bitmap_result};
 }
 
-// Fake that implements the calls to FaviconHalder::Delegate's DownloadImage(),
+// Fake that implements the calls to FaviconHandler::Delegate's DownloadImage(),
 // delegated to this class through MockDelegate.
 class FakeImageDownloader {
  public:
@@ -321,7 +324,7 @@ class FaviconHandlerTest : public testing::Test {
   const GURL kIconURL16x16 = GURL("http://www.google.com/favicon16x16");
   const GURL kIconURL64x64 = GURL("http://www.google.com/favicon64x64");
 
-  FaviconHandlerTest() {
+  FaviconHandlerTest() : download_histogram_(new base::HistogramTester()) {
     // Register various known icon URLs.
     delegate_.fake_downloader().Add(kIconURL10x10, IntVector{10});
     delegate_.fake_downloader().Add(kIconURL12x12, IntVector{12});
@@ -337,10 +340,22 @@ class FaviconHandlerTest : public testing::Test {
         new ui::test::ScopedSetSupportedScaleFactors({ui::SCALE_FACTOR_100P}));
   }
 
+  void TearDown() override {
+    // Check that if any downloads occurred, the attempt count was recorded.
+    if (!download_histogram_name_.empty() && delegate_.downloads().size() > 0) {
+      download_histogram_->ExpectBucketCount(
+          download_histogram_name_,
+          /*sample=*/delegate_.downloads().size(),
+          /*expected_count=*/1);
+    }
+  }
+
   bool VerifyAndClearExpectations() {
     base::RunLoop().RunUntilIdle();
     favicon_service_.fake()->ClearDbRequests();
     delegate_.fake_downloader().ClearDownloads();
+    // Drop download histogram without verification.
+    download_histogram_ = base::MakeUnique<base::HistogramTester>();
     return testing::Mock::VerifyAndClearExpectations(&favicon_service_) &&
            testing::Mock::VerifyAndClearExpectations(&delegate_);
   }
@@ -350,6 +365,10 @@ class FaviconHandlerTest : public testing::Test {
   std::unique_ptr<FaviconHandler> RunHandlerWithCandidates(
       FaviconDriverObserver::NotificationIconType handler_type,
       const std::vector<favicon::FaviconURL>& candidates) {
+    download_histogram_name_ =
+        handler_type == FaviconDriverObserver::TOUCH_LARGEST
+            ? "Favicons.LargeIconDownloadAttempts"
+            : "Favicons.DownloadAttempts";
     auto handler = base::MakeUnique<FaviconHandler>(&favicon_service_,
                                                     &delegate_, handler_type);
     handler->FetchFavicon(kPageURL);
@@ -373,9 +392,11 @@ class FaviconHandlerTest : public testing::Test {
                                     candidates);
   }
 
+  std::string download_histogram_name_;
   base::MessageLoopForUI message_loop_;
   std::unique_ptr<ui::test::ScopedSetSupportedScaleFactors>
       scoped_set_supported_scale_factors_;
+  std::unique_ptr<base::HistogramTester> download_histogram_;
   testing::NiceMock<MockFaviconServiceWithFake> favicon_service_;
   testing::NiceMock<MockDelegate> delegate_;
 };
@@ -607,6 +628,7 @@ TEST_F(FaviconHandlerTest, UpdateDuringDownloading) {
   std::unique_ptr<FaviconHandler> handler =
       RunHandlerWithSimpleFaviconCandidates({kIconURL1, kIconURL2});
 
+  download_histogram_->ExpectTotalCount("Favicons.DownloadAttempts", 0);
   ASSERT_TRUE(VerifyAndClearExpectations());
   ASSERT_TRUE(delegate_.fake_downloader().HasPendingManualCallback());
 
@@ -646,6 +668,7 @@ TEST_F(FaviconHandlerTest, UpdateSameIconURLsWhileProcessingShouldBeNoop) {
 
   ASSERT_THAT(favicon_service_.fake()->db_requests(),
               ElementsAre(kPageURL, kIconURL64x64, kSlowLoadingIconURL));
+  download_histogram_->ExpectTotalCount("Favicons.DownloadAttempts", 0);
   ASSERT_TRUE(VerifyAndClearExpectations());
   ASSERT_TRUE(delegate_.fake_downloader().HasPendingManualCallback());
 
@@ -674,6 +697,10 @@ TEST_F(FaviconHandlerTest, UpdateSameIconURLsAfterFinishedShouldBeNoop) {
   std::unique_ptr<FaviconHandler> handler = RunHandlerWithCandidates(
       FaviconDriverObserver::NON_TOUCH_16_DIP, favicon_urls);
 
+  download_histogram_->ExpectBucketCount(
+      "Favicons.DownloadAttempts",
+      /*sample=*/delegate_.downloads().size(),
+      /*expected_count=*/1);
   ASSERT_TRUE(VerifyAndClearExpectations());
 
   // Calling OnUpdateFaviconURL() with identical data should be a no-op.