Bug 1743914 - Part 2: Allow to experiment with setting Firefox as default PDF handler on Windows 10+. r=mhowell,Mardak

This adds a `setDefaultPDFHandler` that extends the existing
`setDefaultBrowserUserChoice` to also set Firefox as the default PDF
handler when setting Firefox as the default browser.  (Since this uses
User Choice, it's Windows 10+ only.)

Differential Revision: https://phabricator.services.mozilla.com/D132660

browser/app/profile/firefox.js

@@ -282,6 +282,9 @@ pref("browser.shell.defaultBrowserCheckCount", 0);
 // Attempt to set the default browser on Windows 10 using the UserChoice registry keys,
 // before falling back to launching the modern Settings dialog.
 pref("browser.shell.setDefaultBrowserUserChoice", true);
+// When setting the default browser on Windows 10 using the UserChoice
+// registry keys, also try to set Firefox as the default PDF handler.
+pref("browser.shell.setDefaultPDFHandler", false);
 #endif
 
 

browser/components/shell/ShellService.jsm

@@ -120,6 +120,38 @@ let ShellServiceInternal = {
     return false;
   },
 
+  /*
+   * Invoke the Windows Default Browser agent with the given options.
+   *
+   * Separated for easy stubbing in tests.
+   */
+  _callExternalDefaultBrowserAgent(options = {}) {
+    const wdba = Services.dirsvc.get("XREExeF", Ci.nsIFile);
+    wdba.leafName = "default-browser-agent.exe";
+    return Subprocess.call({
+      ...options,
+      command: options.command || wdba.path,
+    });
+  },
+
+  /*
+   * Check if UserChoice is impossible.
+   *
+   * Separated for easy stubbing in tests.
+   *
+   * @return string telemetry result like "Err*", or null if UserChoice
+   * is possible.
+   */
+  _userChoiceImpossibleTelemetryResult() {
+    if (!ShellService.checkAllProgIDsExist()) {
+      return "ErrProgID";
+    }
+    if (!ShellService.checkBrowserUserChoiceHashes()) {
+      return "ErrHash";
+    }
+    return null;
+  },
+
   /*
    * Set the default browser through the UserChoice registry keys on Windows.
    *
@@ -144,24 +176,24 @@ let ShellServiceInternal = {
     let telemetryResult = "ErrOther";
 
     try {
-      if (!ShellService.checkAllProgIDsExist()) {
-        telemetryResult = "ErrProgID";
+      telemetryResult =
+        this._userChoiceImpossibleTelemetryResult() ?? "ErrOther";
+      if (telemetryResult == "ErrProgID") {
         throw new Error("checkAllProgIDsExist() failed");
       }
-
-      if (!ShellService.checkBrowserUserChoiceHashes()) {
-        telemetryResult = "ErrHash";
+      if (telemetryResult == "ErrHash") {
         throw new Error("checkBrowserUserChoiceHashes() failed");
       }
 
-      const wdba = Services.dirsvc.get("XREExeF", Ci.nsIFile);
-      wdba.leafName = "default-browser-agent.exe";
       const aumi = XreDirProvider.getInstallHash();
 
       telemetryResult = "ErrLaunchExe";
-      const exeProcess = await Subprocess.call({
-        command: wdba.path,
-        arguments: ["set-default-browser-user-choice", aumi],
+      const exeArgs = ["set-default-browser-user-choice", aumi];
+      if (NimbusFeatures.shellService.getVariable("setDefaultPDFHandler")) {
+        exeArgs.push(".pdf");
+      }
+      const exeProcess = await this._callExternalDefaultBrowserAgent({
+        arguments: exeArgs,
       });
       telemetryResult = "ErrOther";
 

browser/components/shell/test/browser.ini

@@ -10,6 +10,8 @@ support-files =
 skip-if = os != "mac" || verify
 [browser_doesAppNeedPin.js]
 [browser_setDefaultBrowser.js]
+[browser_setDefaultPDFHandler.js]
+run-if = os == "win"
 [browser_setDesktopBackgroundPreview.js]
 [browser_headless_screenshot_1.js]
 support-files =

browser/components/shell/test/browser_setDefaultPDFHandler.js

@@ -0,0 +1,146 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+XPCOMUtils.defineLazyModuleGetters(this, {
+  ExperimentAPI: "resource://nimbus/ExperimentAPI.jsm",
+  ExperimentFakes: "resource://testing-common/NimbusTestUtils.jsm",
+  NimbusFeatures: "resource://nimbus/ExperimentAPI.jsm",
+  sinon: "resource://testing-common/Sinon.jsm",
+});
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "XreDirProvider",
+  "@mozilla.org/xre/directory-provider;1",
+  "nsIXREDirProvider"
+);
+
+const _callExternalDefaultBrowserAgentStub = sinon
+  .stub(ShellService, "_callExternalDefaultBrowserAgent")
+  .callsFake(async () => ({
+    async wait() {
+      return { exitCode: 0 };
+    },
+  }));
+
+const _userChoiceImpossibleTelemetryResultStub = sinon
+  .stub(ShellService, "_userChoiceImpossibleTelemetryResult")
+  .callsFake(() => null);
+
+// Ensure we don't fall back to a real implementation.
+const setDefaultStub = sinon.stub();
+const shellStub = sinon
+  .stub(ShellService, "shellService")
+  .value({ setDefaultBrowser: setDefaultStub });
+
+registerCleanupFunction(() => {
+  _callExternalDefaultBrowserAgentStub.restore();
+  _userChoiceImpossibleTelemetryResultStub.restore();
+  shellStub.restore();
+
+  ExperimentAPI._store._deleteForTests("shellService");
+});
+
+add_task(async function ready() {
+  await ExperimentAPI.ready();
+});
+
+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: {
+          setDefaultBrowserUserChoice: true,
+          setDefaultPDFHandler: true,
+          enabled: true,
+        },
+        targeting: "true",
+      },
+    });
+
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultBrowserUserChoice"),
+      true
+    );
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultPDFHandler"),
+      true
+    );
+
+    _callExternalDefaultBrowserAgentStub.resetHistory();
+    ShellService.setDefaultBrowser();
+
+    const aumi = XreDirProvider.getInstallHash();
+    Assert.ok(_callExternalDefaultBrowserAgentStub.called);
+    Assert.deepEqual(_callExternalDefaultBrowserAgentStub.firstCall.args, [
+      { arguments: ["set-default-browser-user-choice", aumi, ".pdf"] },
+    ]);
+  });
+
+  add_task(async function remoteEnableWithoutPDF() {
+    await ExperimentFakes.remoteDefaultsHelper({
+      feature: NimbusFeatures.shellService,
+      configuration: {
+        slug: "shellService_remoteEnableWithoutPDF",
+        variables: {
+          setDefaultBrowserUserChoice: true,
+          setDefaultPDFHandler: false,
+          enabled: true,
+        },
+        targeting: "true",
+      },
+    });
+
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultBrowserUserChoice"),
+      true
+    );
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultPDFHandler"),
+      false
+    );
+
+    _callExternalDefaultBrowserAgentStub.resetHistory();
+    ShellService.setDefaultBrowser();
+
+    const aumi = XreDirProvider.getInstallHash();
+    Assert.ok(_callExternalDefaultBrowserAgentStub.called);
+    Assert.deepEqual(_callExternalDefaultBrowserAgentStub.firstCall.args, [
+      { arguments: ["set-default-browser-user-choice", aumi] },
+    ]);
+  });
+
+  add_task(async function remoteDisable() {
+    await ExperimentFakes.remoteDefaultsHelper({
+      feature: NimbusFeatures.shellService,
+      configuration: {
+        slug: "shellService_remoteDisable",
+        variables: {
+          setDefaultBrowserUserChoice: false,
+          setDefaultPDFHandler: true,
+          enabled: false,
+        },
+        targeting: "true",
+      },
+    });
+
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultBrowserUserChoice"),
+      false
+    );
+    Assert.equal(
+      NimbusFeatures.shellService.getVariable("setDefaultPDFHandler"),
+      true
+    );
+
+    _callExternalDefaultBrowserAgentStub.resetHistory();
+    ShellService.setDefaultBrowser();
+
+    Assert.ok(_callExternalDefaultBrowserAgentStub.notCalled);
+    Assert.ok(setDefaultStub.called);
+  });
+}

toolkit/components/nimbus/FeatureManifest.yaml

@@ -225,6 +225,10 @@ shellService:
       type: boolean
       fallbackPref: browser.shell.setDefaultBrowserUserChoice
       description: Should it set as default browser
+    setDefaultPDFHandler:
+      type: boolean
+      fallbackPref: browser.shell.setDefaultPDFHandler
+      description: Should setting it as the default browser set it as the default PDF handler.
 upgradeDialog:
   description: The dialog shown for major upgrades
   hasExposure: false