Bug 1743914 - Part 3: Telemetry for when Firefox is the default handler. r=chutten,mhowell

This only records whether Firefox is the default PDF handler for now.
But it will accommodate additional file types and protocols in the
future, should they be desired.

This is Windows 10+ only, since we really only care about PDF handling
defaults where Edgium is the OS default.

Differential Revision: https://phabricator.services.mozilla.com/D132659

browser/components/BrowserGlue.jsm

@@ -82,6 +82,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   SearchSERPTelemetry: "resource:///modules/SearchSERPTelemetry.jsm",
   SessionStartup: "resource:///modules/sessionstore/SessionStartup.jsm",
   SessionStore: "resource:///modules/sessionstore/SessionStore.jsm",
+  ShellService: "resource:///modules/ShellService.jsm",
   ShortcutUtils: "resource://gre/modules/ShortcutUtils.jsm",
   TabCrashHandler: "resource:///modules/ContentCrashHandlers.jsm",
   TabUnloader: "resource:///modules/TabUnloader.jsm",
@@ -2465,6 +2466,19 @@ BrowserGlue.prototype = {
         },
       },
 
+      // Report whether Firefox is the default handler for various files types,
+      // in particular, ".pdf".
+      {
+        condition: AppConstants.platform == "win",
+        task: () => {
+          Services.telemetry.keyedScalarSet(
+            "os.environment.is_default_handler",
+            ".pdf",
+            ShellService.isDefaultHandlerFor(".pdf")
+          );
+        },
+      },
+
       // Install built-in themes. We already installed the active built-in
       // theme, if any, before UI startup.
       {

browser/components/shell/ShellService.jsm

@@ -289,6 +289,21 @@ let ShellServiceInternal = {
       .add(setAsDefaultError);
   },
 
+  /**
+   * Determine if we're the default handler for the given file extension (like
+   * ".pdf") or protocol (like "https").  Windows-only for now.
+   *
+   * @returns true if we are the default handler, false otherwise.
+   */
+  isDefaultHandlerFor(aFileExtensionOrProtocol) {
+    if (AppConstants.platform == "win") {
+      return this.shellService
+        .QueryInterface(Ci.nsIWindowsShellService)
+        .isDefaultHandlerFor(aFileExtensionOrProtocol);
+    }
+    return false;
+  },
+
   /**
    * Checks if Firefox app can and isn't pinned to OS "taskbar."
    *

browser/components/shell/nsIWindowsShellService.idl

@@ -108,4 +108,11 @@ interface nsIWindowsShellService : nsISupports
    */
   bool checkAllProgIDsExist();
   bool checkBrowserUserChoiceHashes();
+
+  /*
+   * Determines whether or not Firefox is the "Default Handler", i.e.,
+   * is registered to handle, the given file extension (like ".pdf")
+   * or protocol (like "https").
+   */
+  boolean isDefaultHandlerFor(in AString aFileExtensionOrProtocol);
 };

browser/components/shell/nsWindowsShellService.cpp

@@ -207,6 +207,32 @@ nsWindowsShellService::IsDefaultBrowser(bool aForAllTypes,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsWindowsShellService::IsDefaultHandlerFor(
+    const nsAString& aFileExtensionOrProtocol, bool* aIsDefaultHandlerFor) {
+  *aIsDefaultHandlerFor = false;
+
+  RefPtr<IApplicationAssociationRegistration> pAAR;
+  HRESULT hr = CoCreateInstance(
+      CLSID_ApplicationAssociationRegistration, nullptr, CLSCTX_INPROC,
+      IID_IApplicationAssociationRegistration, getter_AddRefs(pAAR));
+  if (FAILED(hr)) {
+    return NS_OK;
+  }
+
+  wchar_t exePath[MAXPATHLEN] = L"";
+  nsresult rv = BinaryPath::GetLong(exePath);
+
+  if (NS_FAILED(rv)) {
+    return NS_OK;
+  }
+
+  const nsString& flatClass = PromiseFlatString(aFileExtensionOrProtocol);
+
+  *aIsDefaultHandlerFor = IsPathDefaultForClass(pAAR, exePath, flatClass.get());
+  return NS_OK;
+}
+
 nsresult nsWindowsShellService::LaunchControlPanelDefaultsSelectionUI() {
   IApplicationAssociationRegistrationUI* pAARUI;
   HRESULT hr = CoCreateInstance(

browser/components/shell/test/browser_setDefaultPDFHandler.js

@@ -49,17 +49,13 @@ if (AppConstants.isPlatformAndVersionAtLeast("win", "10")) {
   // Everything here is Windows 10+.
 
   add_task(async function remoteEnableWithPDF() {
-    await ExperimentFakes.remoteDefaultsHelper({
-      feature: NimbusFeatures.shellService,
-      configuration: {
-        slug: "shellService_remoteEnableWithPDF",
-        variables: {
+    let doCleanup = await ExperimentFakes.enrollWithRollout({
+      featureId: NimbusFeatures.shellService.featureId,
+      value: {
         setDefaultBrowserUserChoice: true,
         setDefaultPDFHandler: true,
         enabled: true,
       },
-        targeting: "true",
-      },
     });
 
     Assert.equal(
@@ -79,20 +75,18 @@ if (AppConstants.isPlatformAndVersionAtLeast("win", "10")) {
     Assert.deepEqual(_callExternalDefaultBrowserAgentStub.firstCall.args, [
       { arguments: ["set-default-browser-user-choice", aumi, ".pdf"] },
     ]);
+
+    await doCleanup();
   });
 
   add_task(async function remoteEnableWithoutPDF() {
-    await ExperimentFakes.remoteDefaultsHelper({
-      feature: NimbusFeatures.shellService,
-      configuration: {
-        slug: "shellService_remoteEnableWithoutPDF",
-        variables: {
+    let doCleanup = await ExperimentFakes.enrollWithRollout({
+      featureId: NimbusFeatures.shellService.featureId,
+      value: {
         setDefaultBrowserUserChoice: true,
         setDefaultPDFHandler: false,
         enabled: true,
       },
-        targeting: "true",
-      },
     });
 
     Assert.equal(
@@ -112,20 +106,18 @@ if (AppConstants.isPlatformAndVersionAtLeast("win", "10")) {
     Assert.deepEqual(_callExternalDefaultBrowserAgentStub.firstCall.args, [
       { arguments: ["set-default-browser-user-choice", aumi] },
     ]);
+
+    await doCleanup();
   });
 
   add_task(async function remoteDisable() {
-    await ExperimentFakes.remoteDefaultsHelper({
-      feature: NimbusFeatures.shellService,
-      configuration: {
-        slug: "shellService_remoteDisable",
-        variables: {
+    let doCleanup = await ExperimentFakes.enrollWithRollout({
+      featureId: NimbusFeatures.shellService.featureId,
+      value: {
         setDefaultBrowserUserChoice: false,
         setDefaultPDFHandler: true,
         enabled: false,
       },
-        targeting: "true",
-      },
     });
 
     Assert.equal(
@@ -142,5 +134,7 @@ if (AppConstants.isPlatformAndVersionAtLeast("win", "10")) {
 
     Assert.ok(_callExternalDefaultBrowserAgentStub.notCalled);
     Assert.ok(setDefaultStub.called);
+
+    await doCleanup();
   });
 }

browser/components/tests/browser/browser_browserGlue_telemetry.js

@@ -45,3 +45,42 @@ add_task(function check_startup_pinned_telemetry() {
       break;
   }
 });
+
+// Check that telemetry reports whether Firefox is the default PDF handler.
+// This is safe without any explicit coordination because idle tasks are
+// guaranteed to have been invokedbefore the test harness invokes the test.  See
+// https://searchfox.org/mozilla-central/rev/1674b86019a96f076e0f98f1d0f5f3ab9d4e9020/browser/components/BrowserGlue.jsm#2320-2324
+// and
+// https://searchfox.org/mozilla-central/rev/1674b86019a96f076e0f98f1d0f5f3ab9d4e9020/browser/base/content/browser.js#2364.
+add_task(function check_is_default_handler_telemetry() {
+  const scalars = TelemetryTestUtils.getProcessScalars("parent", true);
+
+  // Check the appropriate telemetry is set or not reported by platform.
+  switch (AppConstants.platform) {
+    case "win":
+      // We should always set whether we're the default PDF handler.
+      Assert.ok("os.environment.is_default_handler" in scalars);
+      Assert.deepEqual(
+        [".pdf"],
+        Object.keys(scalars["os.environment.is_default_handler"])
+      );
+
+      if (Cu.isInAutomation) {
+        // But only in automation can we assume we're not the default handler.
+        TelemetryTestUtils.assertKeyedScalar(
+          scalars,
+          "os.environment.is_default_handler",
+          ".pdf",
+          false,
+          "Not default PDF handler on Windows"
+        );
+      }
+      break;
+    default:
+      TelemetryTestUtils.assertScalarUnset(
+        scalars,
+        "os.environment.is_default_handler"
+      );
+      break;
+  }
+});

toolkit/components/telemetry/Scalars.yaml

@@ -1922,6 +1922,29 @@ os.environment:
     operating_systems:
       - windows
 
+  is_default_handler:
+    bug_numbers:
+      - 1743914
+    description: >
+      Records whether Firefox was the default handler for particular file types
+      or protocols.  The result is split into keys which represent the file
+      extension: currently, a subset of the file types Firefox registers to
+      handle, namely ".pdf".  In the future, more file types may be recorded,
+      and/or a subset of the protocol schemes that Firefox registers to may be
+      recorded.
+    keyed: true
+    expires: "106"
+    kind: boolean
+    notification_emails:
+      - application-update-telemetry-alerts@mozilla.com
+    release_channel_collection: opt-out
+    products:
+      - firefox
+    record_in_processes:
+      - main
+    operating_systems:
+      - windows
+
   is_kept_in_dock:
     bug_numbers:
       - 1715348