[CrOS MultiDevice] Add metric for Messages PWA uninstallation.

This metric measures the boolean success/failure result of the app
uninstallation.

Bug: 917855
Change-Id: Iad12046f28b647cf58cb6f22aa6862ff086204ef
Reviewed-on: https://chromium-review.googlesource.com/c/1392011Reviewed-by: Jeremy Klein <jlklein@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619832}

chrome/browser/chromeos/multidevice_setup/android_sms_app_helper_delegate_impl.cc

@@ -38,11 +38,12 @@ network::mojom::CookieManager* GetCookieManager(Profile* profile) {
 }
 
 void OnAppUninstallResult(const GURL& app_url, bool succeeded) {
+  UMA_HISTOGRAM_BOOLEAN("AndroidSms.PWAUninstallationResult", succeeded);
+
   if (succeeded)
     return;
 
   PA_LOG(ERROR) << "Failed to uninstall messages app; URL: " << app_url;
-  // TODO(khorimoto): Add metrics for failed uninstallations.
 }
 
 }  // namespace

chrome/browser/chromeos/multidevice_setup/android_sms_app_helper_delegate_impl_unittest.cc

@@ -248,6 +248,8 @@ TEST_F(AndroidSmsAppHelperDelegateImplTest, TestInstallMessagesApp_NoOldApp) {
 
 TEST_F(AndroidSmsAppHelperDelegateImplTest,
        TestInstallMessagesApp_UninstallsOldApp) {
+  base::HistogramTester histogram_tester;
+
   // Simulate a PWA having already been installed at the old URL.
   test_pwa_fetcher_delegate()->SetHasPwa(
       android_sms::GetAndroidMessagesURLOld(), true /* has_pwa */);
@@ -258,6 +260,8 @@ TEST_F(AndroidSmsAppHelperDelegateImplTest,
   ASSERT_EQ(1u, test_pending_app_manager()->uninstall_requests().size());
   EXPECT_EQ(android_sms::GetAndroidMessagesURLOld(),
             test_pending_app_manager()->uninstall_requests()[0]);
+  histogram_tester.ExpectBucketCount("AndroidSms.PWAUninstallationResult",
+                                     true /* success */, 1);
 
   // The old app's cookie should have been deleted.
   VerifyCookieDeletedForUrl(android_sms::GetAndroidMessagesURLOld());

tools/metrics/histograms/histograms.xml

@@ -2923,6 +2923,16 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="AndroidSms.PWAUninstallationResult" enum="BooleanSuccess">
+  <owner>azeemarshad@chromium.org</owner>
+  <owner>hansberry@chromium.org</owner>
+  <summary>
+    Records success/failure for when Android Messages for Web PWA is
+    uninstalled. The PWA is uninstalled when the messages URL changes, resulting
+    in the PWA being uninstalled at the old URL and reinstalled at the new URL.
+  </summary>
+</histogram>
+
 <histogram name="AndroidSms.ServiceWorkerLifetime" units="ms">
   <owner>azeemarshad@chromium.org</owner>
   <summary>