Bug 1809422 - Android Unable to Print/Save PDF r=geckoview-reviewers,calu

The canonical browsing context is not available if the current window/tab
is not focused for printing or saving as a PDF.

This patch adds a call to `setFocused` before creating a Gecko PDF to
ensure the canonical browsing context can be used for generating a PDF
to save or print.

Differential Revision: https://phabricator.services.mozilla.com/D185311

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/PrintDelegateTest.kt

@@ -322,4 +322,25 @@ class PrintDelegateTest : BaseSessionTest() {
             )
         }
     }
+
+    @NullDelegate(Autofill.Delegate::class)
+    @Test
+    fun availableCanonicalBrowsingContext() {
+        sessionRule.setPrefsUntilTestEnd(mapOf("dom.enable_window_print" to true))
+        activityRule.scenario.onActivity { activity ->
+            // CSS rules render this blue on screen and orange on print
+            mainSession.loadTestPath(ORANGE_PDF_PATH)
+            mainSession.waitForPageStop()
+            // Setting to the default delegate (test rules changed it)
+            mainSession.printDelegate = activity.view.printDelegate
+            mainSession.setFocused(false)
+            mainSession.printPageContent()
+            val centerPixel = printCenterPixelColor()
+            val orange = rgb(255, 113, 57)
+            assertTrue(
+                "Android print opened and rendered.",
+                sessionRule.waitForResult(centerPixel) == orange,
+            )
+        }
+    }
 }

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoSession.java

@@ -7542,6 +7542,8 @@ public class GeckoSession {
       final @Nullable Long browsingContextId) {
     final GeckoResult<InputStream> geckoResult = new GeckoResult<>();
     if (browsingContextId == null) {
+      // Ensures the canonical browsing context is available
+      setFocused(true);
       this.mWindow.printToPdf(geckoResult);
     } else {
       this.mWindow.printToPdf(geckoResult, browsingContextId);