SkPDF: allow PDF module to be disabled in DM and SampleApp

tests/CanvasTest.cpp

Index: tests/CanvasTest.cpp
diff --git a/tests/CanvasTest.cpp b/tests/CanvasTest.cpp
index 970a37074f4124ebdda500fee94a20986bd33343..78253ac900166f590bc28aa0087af40738813ebb 100644
--- a/tests/CanvasTest.cpp
+++ b/tests/CanvasTest.cpp
@@ -568,6 +568,8 @@ static void TestPdfDevice(skiatest::Reporter* reporter,
                           CanvasTestStep* testStep) {
     SkDynamicMemoryWStream outStream;
     SkAutoTUnref<SkDocument> doc(SkDocument::CreatePDF(&outStream));
+#if SK_SUPPORT_PDF
+    REPORTER_ASSERT(reporter, doc);
     SkCanvas* canvas = doc->beginPage(SkIntToScalar(d.fWidth),
                                       SkIntToScalar(d.fHeight));
     REPORTER_ASSERT(reporter, canvas);
@@ -575,6 +577,9 @@ static void TestPdfDevice(skiatest::Reporter* reporter,
     testStep->draw(canvas, d, reporter);
 
     REPORTER_ASSERT(reporter, doc->close());
+#else
+    REPORTER_ASSERT(reporter, !doc);
+#endif  // SK_SUPPORT_PDF
 }
 
 // The following class groups static functions that need to access