Handle SkBitmaps which have no pixels in SkPDFImage.

A test that ensures this no longer crashes has been added.

BUG=skia:3232

Review URL: https://codereview.chromium.org/802713002

gyp/tests.gypi

@@ -147,6 +147,7 @@
     '../tests/NameAllocatorTest.cpp',
     '../tests/OSPathTest.cpp',
     '../tests/OnceTest.cpp',
+    '../tests/PDFInvalidBitmapTest.cpp',
     '../tests/PDFJpegEmbedTest.cpp',
     '../tests/PDFPrimitivesTest.cpp',
     '../tests/PackBitsTest.cpp',

src/pdf/SkPDFImage.cpp

@@ -222,7 +222,11 @@ static SkStream* extract_image_data(const SkBitmap& bitmap,
     bool transparent = extractAlpha;
     SkStream* stream = NULL;
 
-    bitmap.lockPixels();
+    SkAutoLockPixels lock(bitmap);
+    if (NULL == bitmap.getPixels()) {
+        return NULL;
+    }
+
     switch (colorType) {
         case kIndex_8_SkColorType:
             if (!extractAlpha) {
@@ -253,7 +257,6 @@ static SkStream* extract_image_data(const SkBitmap& bitmap,
         default:
             SkASSERT(false);
     }
-    bitmap.unlockPixels();
 
     if (isTransparent != NULL) {
         *isTransparent = transparent;

tests/PDFInvalidBitmapTest.cpp

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkDocument.h"
+#include "SkImageInfo.h"
+#include "SkPixelRef.h"
+#include "SkRefCnt.h"
+#include "SkStream.h"
+
+#include "Test.h"
+
+namespace {
+
+// SkPixelRef which fails to lock, as a lazy pixel ref might if its pixels
+// cannot be generated.
+class InvalidPixelRef : public SkPixelRef {
+public:
+    InvalidPixelRef(const SkImageInfo& info) : SkPixelRef(info) {}
+private:
+    virtual bool onNewLockPixels(LockRec*) SK_OVERRIDE { return false; }
+    virtual void onUnlockPixels() SK_OVERRIDE {
+        SkDEBUGFAIL("InvalidPixelRef can't be locked");
+    }
+};
+
+SkBitmap make_invalid_bitmap(const SkImageInfo& imageInfo) {
+    SkBitmap bitmap;
+    bitmap.setInfo(imageInfo);
+    bitmap.setPixelRef(SkNEW_ARGS(InvalidPixelRef, (imageInfo)))->unref();
+    return bitmap;
+}
+
+SkBitmap make_invalid_bitmap(SkColorType colorType) {
+    return make_invalid_bitmap(
+        SkImageInfo::Make(100, 100, colorType, kPremul_SkAlphaType));
+}
+
+}  // namespace
+
+DEF_TEST(PDFInvalidBitmap, reporter) {
+    SkDynamicMemoryWStream stream;
+    SkAutoTUnref<SkDocument> document(SkDocument::CreatePDF(&stream));
+    SkCanvas* canvas = document->beginPage(100, 100);
+
+    canvas->drawBitmap(SkBitmap(), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(SkImageInfo()), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(kN32_SkColorType), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(kIndex_8_SkColorType), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(kARGB_4444_SkColorType), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(kRGB_565_SkColorType), 0, 0);
+    canvas->drawBitmap(make_invalid_bitmap(kAlpha_8_SkColorType), 0, 0);
+
+    // This test passes if it does not crash.
+}