SkPDF: flip saveLayer rightside up

src/pdf/SkPDFDevice.cpp

Index: src/pdf/SkPDFDevice.cpp
diff --git a/src/pdf/SkPDFDevice.cpp b/src/pdf/SkPDFDevice.cpp
index 92f190732f748a3cfaf3dc49bef18e1e9fd3e65f..1720cd8df2c8664539b61a9dc84acfb0b15411f2 100644
--- a/src/pdf/SkPDFDevice.cpp
+++ b/src/pdf/SkPDFDevice.cpp
@@ -1588,9 +1588,16 @@ void SkPDFDevice::appendDestinations(SkPDFDict* dict, SkPDFObject* page) const {
 }
 
 sk_sp<SkPDFObject> SkPDFDevice::makeFormXObjectFromDevice() {
+    SkMatrix inverseTransform = SkMatrix::I();
+    if (!this->initialTransform().isIdentity()) {
+        if (!this->initialTransform().invert(&inverseTransform)) {
+            SkDEBUGFAIL("Layer initial transform should be invertible.");
+            inverseTransform.reset();
+        }
+    }
     sk_sp<SkPDFObject> xobject =
         SkPDFMakeFormXObject(this->content(), this->copyMediaBox(),
-                             this->makeResourceDict(), nullptr);
+                             this->makeResourceDict(), inverseTransform, nullptr);
     // We always draw the form xobjects that we create back into the device, so
     // we simply preserve the font usage instead of pulling it out and merging
     // it back in later.