Bug 1790855 - Enable screenshots button on about pages when screenshots component is enabled. r=sfoster

Differential Revision: https://phabricator.services.mozilla.com/D157355

browser/base/content/browser.js

@@ -547,6 +547,34 @@ XPCOMUtils.defineLazyPreferenceGetter(
   true
 );
 
+XPCOMUtils.defineLazyPreferenceGetter(
+  this,
+  "gScreenshotsDisabled",
+  "extensions.screenshots.disabled",
+  false,
+  () => {
+    Services.obs.notifyObservers(
+      window,
+      "toggle-screenshot-disable",
+      gScreenshots.shouldScreenshotsButtonBeDisabled()
+    );
+  }
+);
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  this,
+  "gScreenshotsComponentEnabled",
+  "screenshots.browser.component.enabled",
+  false,
+  () => {
+    Services.obs.notifyObservers(
+      window,
+      "toggle-screenshot-disable",
+      gScreenshots.shouldScreenshotsButtonBeDisabled()
+    );
+  }
+);
+
 customElements.setElementCreationCallback("translation-notification", () => {
   Services.scriptloader.loadSubScript(
     "chrome://browser/content/translation-notification.js",
@@ -679,6 +707,25 @@ var gNavigatorBundle = {
   },
 };
 
+var gScreenshots = {
+  shouldScreenshotsButtonBeDisabled(uri) {
+    // About pages other than about:reader are not currently supported by
+    // the screenshots extension (see Bug 1620992).
+    let shouldBeDisabled;
+    if (uri) {
+      shouldBeDisabled =
+        gScreenshotsDisabled ||
+        (!gScreenshotsComponentEnabled &&
+          uri.scheme === "about" &&
+          !uri.spec.startsWith("about:reader"));
+    } else {
+      shouldBeDisabled = gScreenshotsDisabled || !gScreenshotsComponentEnabled;
+    }
+
+    return shouldBeDisabled;
+  },
+};
+
 function updateFxaToolbarMenu(enable, isInitialUpdate = false) {
   // We only show the Firefox Account toolbar menu if the feature is enabled and
   // if sync is enabled.
@@ -5441,14 +5488,13 @@ var XULBrowserWindow = {
       closeOpenPanels("panel[locationspecific='true']");
     }
 
-    // About pages other than about:reader are not currently supported by
-    // screenshots (see Bug 1620992).
+    let screenshotsButtonsDisabled = gScreenshots.shouldScreenshotsButtonBeDisabled(
+      aLocationURI
+    );
     Services.obs.notifyObservers(
       window,
       "toggle-screenshot-disable",
-      (aLocationURI.scheme == "about" &&
-        !aLocationURI.spec.startsWith("about:reader")) ||
-        Services.prefs.getBoolPref("extensions.screenshots.disabled")
+      screenshotsButtonsDisabled
     );
 
     gPermissionPanel.onLocationChange();

browser/base/content/nsContextMenu.js

@@ -1280,8 +1280,7 @@ class nsContextMenu {
     // screenshots (see Bug 1620992)
     let uri = this.contentData?.documentURIObject;
     let shouldShow =
-      !screenshotsDisabled &&
-      (uri.scheme != "about" || uri.spec.startsWith("about:reader")) &&
+      !gScreenshots.shouldScreenshotsButtonBeDisabled(uri) &&
       this.inTabBrowser &&
       !this.onTextInput &&
       !this.onLink &&

browser/components/screenshots/tests/browser/browser_screenshots_test_toolbar_button.js

@@ -19,8 +19,8 @@ add_task(async function testScreenshotButtonDisabled() {
   await BrowserTestUtils.withNewTab("about:home", () => {
     Assert.equal(
       screenshotBtn.disabled,
-      true,
-      "Screenshots button is now disabled"
+      false,
+      "Screenshots button is still enabled on about pages"
     );
   });
 });