Bug 1641064 - Fail screenshot captures immediately if we pause the compositor r=geckoview-reviewers,agi

Differential Revision: https://phabricator.services.mozilla.com/D78373

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

@@ -27,6 +27,7 @@ import kotlin.math.max
 import android.graphics.BitmapFactory
 import android.graphics.Bitmap
 import androidx.test.platform.app.InstrumentationRegistry
+import java.lang.IllegalStateException
 import java.lang.NullPointerException
 
 
@@ -141,6 +142,18 @@ class ScreenshotTest : BaseSessionTest() {
         }
     }
 
+    @WithDisplay(height = SCREEN_HEIGHT, width = SCREEN_WIDTH)
+    @Test(expected = IllegalStateException::class)
+    fun capturePixelsFailsCompositorPaused() {
+        sessionRule.display?.let {
+            it.surfaceDestroyed()
+            val result = it.capturePixels()
+            it.surfaceDestroyed()
+
+            sessionRule.waitForResult(result)
+        }
+    }
+
     @WithDisplay(height = SCREEN_HEIGHT, width = SCREEN_WIDTH)
     @Test
     fun screenshotToBitmap() {

widget/android/nsWindow.cpp

@@ -1037,6 +1037,20 @@ class nsWindow::LayerViewSupport final
       mCompositorPaused = true;
       child->Pause();
     }
+
+    if (LockedWindowPtr lock{mWindow}) {
+      while (!mCapturePixelsResults.empty()) {
+        auto result =
+            java::GeckoResult::LocalRef(mCapturePixelsResults.front().mResult);
+        if (result) {
+          result->CompleteExceptionally(
+              java::sdk::IllegalStateException::New(
+                  "The compositor has detached from the session")
+                  .Cast<jni::Throwable>());
+        }
+        mCapturePixelsResults.pop();
+      }
+    }
   }
 
   void SyncResumeCompositor() {
@@ -1205,22 +1219,21 @@ class nsWindow::LayerViewSupport final
 
   void RecvScreenPixels(Shmem&& aMem, const ScreenIntSize& aSize) {
     MOZ_ASSERT(AndroidBridge::IsJavaUiThread());
-    CaptureRequest aCaptureRequest;
-    java::GeckoResult::LocalRef aResult = nullptr;
+    CaptureRequest request;
+    java::GeckoResult::LocalRef result = nullptr;
     if (LockedWindowPtr window{mWindow}) {
-      aCaptureRequest = mCapturePixelsResults.front();
-      aResult = java::GeckoResult::LocalRef(aCaptureRequest.mResult);
-      if (aResult) {
+      request = mCapturePixelsResults.front();
+      result = java::GeckoResult::LocalRef(request.mResult);
+      if (result) {
         mCapturePixelsResults.pop();
       }
     }
 
-    if (aResult) {
+    if (result) {
       auto pixels = mozilla::jni::ByteBuffer::New(
-          FlipScreenPixels(aMem, aSize, aCaptureRequest.mSource,
-                           aCaptureRequest.mOutputSize),
+          FlipScreenPixels(aMem, aSize, request.mSource, request.mOutputSize),
           aMem.Size<int8_t>());
-      aResult->Complete(pixels);
+      result->Complete(pixels);
     }
 
     // Pixels have been copied, so Dealloc Shmem