WIP: Implement APNG

third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..4ecabe272a782eeea22f5c2d9aa405c8a0c84792
--- /dev/null
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
@@ -0,0 +1,565 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/image-decoders/png/PNGImageDecoder.h"
+
+#include "png.h"
+#include "platform/image-decoders/ImageDecoderTestHelpers.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include <memory>
+
+namespace blink {
+
+namespace {
+
+std::unique_ptr<ImageDecoder> createDecoder(ImageDecoder::AlphaOption alphaOption)
+{
+    return wrapUnique(new PNGImageDecoder(alphaOption,
+                                          ImageDecoder::GammaAndColorProfileApplied,
+                                          ImageDecoder::noDecodedImageByteLimit));
+}
+
+std::unique_ptr<ImageDecoder> createDecoder()
+{
+    return createDecoder(ImageDecoder::AlphaNotPremultiplied);
+}
+
+std::unique_ptr<ImageDecoder> createDecoderWithPngData(const char* pngFile)
+{
+    auto decoder = createDecoder();
+    auto data = readFile(pngFile);
+    EXPECT_FALSE(data->isEmpty());
+    decoder->setData(data.get(), true);
+    return decoder;
+}
+
+void testSize(const char* pngFile, IntSize expectedSize)
+{
+    auto decoder = createDecoderWithPngData(pngFile);
+    EXPECT_TRUE(decoder->isSizeAvailable());
+    EXPECT_EQ(expectedSize, decoder->size());
+}
+
+void writeUint32(uint32_t val, png_byte* data)
+{
+    data[0] = val >> 24;
+    data[1] = val >> 16;
+    data[2] = val >> 8;
+    data[3] = val;
+}
+
+void testRepetitionCount(const char* pngFile, int expectedRepetitionCount)
+{
+    auto decoder = createDecoderWithPngData(pngFile);
+    // Decode frame count should see the number of repetitions as well.
+    decoder->frameCount();
+    EXPECT_FALSE(decoder->failed());
+    EXPECT_EQ(expectedRepetitionCount, decoder->repetitionCount());
+}
+
+// Test whether querying for the size of the image works if we present the
+// data byte by byte.
+void testSizeByteByByte(const char *pngFile, size_t bytesNeededToDecodeSize,
+                        IntSize expectedSize)
+{
+    auto decoder = createDecoder();
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+    ASSERT_LT(bytesNeededToDecodeSize, data->size());
+
+    for (size_t length = 1; length <= bytesNeededToDecodeSize; length++) {
+        RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(),
+                                                             length);
+        decoder->setData(tempData.get(), false);
+
+        if (length < bytesNeededToDecodeSize) {
+            EXPECT_FALSE(decoder->isSizeAvailable());
+            EXPECT_TRUE(decoder->size().isEmpty());
+            EXPECT_FALSE(decoder->failed());
+        } else {
+            EXPECT_TRUE(decoder->isSizeAvailable());
+            EXPECT_EQ(expectedSize, decoder->size());
+        }
+    }
+    EXPECT_FALSE(decoder->failed());
+}
+
+struct PublicFrameInfo {
+    size_t duration;
+    IntRect frameRect;
+    ImageFrame::AlphaBlendSource alphaBlend;
+    ImageFrame::DisposalMethod disposalMethod;
+};
+
+// This is the frame data for the following PNG image:
+// /LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png
+static PublicFrameInfo pngAnimatedFrameInfo[] = {
+    {500,  {IntPoint(0, 0), IntSize(5, 5)}, ImageFrame::BlendAtopBgcolor,
+        ImageFrame::DisposeKeep},
+    {900,  {IntPoint(1, 1), IntSize(3, 1)}, ImageFrame::BlendAtopBgcolor,
+        ImageFrame::DisposeOverwriteBgcolor},
+    {2000, {IntPoint(1, 2), IntSize(3, 2)}, ImageFrame::BlendAtopPreviousFrame,
+        ImageFrame::DisposeKeep},
+    {1500, {IntPoint(1, 2), IntSize(3, 1)}, ImageFrame::BlendAtopBgcolor,
+        ImageFrame::DisposeKeep},
+};
+
+void compareFrameWithExpectation(const PublicFrameInfo& expected,
+                                 const ImageFrame* frame)
+{
+    EXPECT_EQ(expected.duration, frame->duration());
+    EXPECT_EQ(expected.frameRect, frame->originalFrameRect());
+    EXPECT_EQ(expected.disposalMethod, frame->getDisposalMethod());
+    EXPECT_EQ(expected.alphaBlend, frame->getAlphaBlendSource());
+}
+
+// This function removes |length| bytes at |offset|, and then calls frameCount.
+// It assumes the missing bytes should return in a failed decoding.

[scroggo_chromium, 2016/10/25 14:59:06]

I think you mean "result" instead of "return"?

(Also, I think "a failed decode" sounds better than "decoding" here.)

+void testMissingDataBreaksDecoding(const char* pngFile, size_t offset,
+                                   size_t length)
+{
+    auto decoder = createDecoder();
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+    
+    RefPtr<SharedBuffer> invalidData = SharedBuffer::create(data->data(),
+                                                            offset);
+    invalidData->append(SharedBuffer::create(data->data() + offset + length,
+                                             data->size() - offset - length));
+    ASSERT_EQ(data->size() - length,  invalidData->size());
+
+    decoder->setData(invalidData, true);
+    decoder->frameCount();
+    EXPECT_TRUE(decoder->failed());
+}
+
+// Decoding up to the indicated fcTL offset and then provide an fcTL with
+// the wrong chunk size (20 instead of 26). It should break the decoder.
+void testInvalidFctlSize(const char *pngFile, size_t offsetFctl,

[scroggo_chromium, 2016/10/25 14:59:06]

* should go next to the type (although I think Matt said the auto-formatter
corrects it to be next to the name :(

+                         size_t expectedFrameCountBeforeFail)
+{
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+
+    auto decoder = createDecoder();
+    RefPtr<SharedBuffer> invalidData = SharedBuffer::create(data->data(),
+                                                            offsetFctl);
+    
+    // Test if this gives the correct frame count, before the fcTL is parsed.
+    decoder->setData(invalidData, false);
+    EXPECT_EQ(expectedFrameCountBeforeFail, decoder->frameCount());
+    ASSERT_FALSE(decoder->failed());
+
+    // Append the wrong size to the data stream
+    png_byte sizeChunk[4];
+    writeUint32(20, sizeChunk);
+    invalidData->append(const_cast<const char*>(

[scroggo_chromium, 2016/10/25 14:59:06]

I don't think you should need a const cast to cast from non-const to const.

+                            reinterpret_cast<char*>(sizeChunk)), 4u);
+    
+    // Skip the size in the original data, but provide the rest of the fcTL
+    invalidData->append(data->data() + offsetFctl + 4, 34u);

[scroggo_chromium, 2016/10/25 14:59:06]

Where did 34u come from? Is fcTL 38 bytes?

[joostouwerling, 2016/10/26 15:44:17]

Yes, 26 bytes of data and 12 for length, tag and crc. I'll make the comment more
explicit on this, as well as for the other numbers in the tests. 

+
+    decoder->setData(invalidData, false);
+    decoder->frameCount();
+    EXPECT_TRUE(decoder->failed());
+}
+
+void testDifferentActlFrameCountIsIgnored(const char* pngFile,
+                                          size_t offsetActl,
+                                          size_t injectedFrameCount,
+                                          size_t expectedFrameCount)
+{
+    auto data = readFile(pngFile);
+    auto decoder = createDecoder();
+    ASSERT_FALSE(data->isEmpty());
+    
+    RefPtr<SharedBuffer> diffActlData = SharedBuffer::create(data->data(),
+                                                             offsetActl + 8);
+    // Write the injectedFrameCount to the stream
+    png_byte sizeChunk[4];
+    writeUint32(injectedFrameCount, sizeChunk);
+    diffActlData->append(const_cast<const char*>(
+                            reinterpret_cast<char*>(sizeChunk)), 4u);
+    // Append the rest of the data
+    diffActlData->append(data->data() + offsetActl + 12,

[scroggo_chromium, 2016/10/25 14:59:06]

I take it the acTL chunk is 16 bytes? It would be good to add comments
explaining these.

+                         data->size() - offsetActl - 12);
+    
+    decoder->setData(diffActlData, true);
+    EXPECT_EQ(expectedFrameCount, decoder->frameCount());

[scroggo_chromium, 2016/10/25 14:59:06]

Maybe assert that expectedFrameCount != injectedFrameCount? If they are the
same, this test is not very informative.

+}
+
+// Test if the frame bitmap hashes of truncated decoding are equal to the 
+// hashes found by incremental decoding.
+void testProgressiveDecoding(const char *pngFile)
+{
+    RefPtr<SharedBuffer> fullData = readFile(pngFile);
+    ASSERT_TRUE(fullData.get());
+    const size_t fullLength = fullData->size();
+
+    std::unique_ptr<ImageDecoder>  decoder;

[scroggo_chromium, 2016/10/25 14:59:06]

nit: extra space

+    ImageFrame* frame;
+
+    Vector<unsigned> truncatedHashes;
+    Vector<unsigned> progressiveHashes;
+
+    // Compute hashes when the file is truncated.
+    const size_t increment = 10;
+    for (size_t i = 1; i <= fullLength; i += increment) {
+        decoder = createDecoder();
+        RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), i);
+        decoder->setData(data.get(), i == fullLength);
+        size_t frameCount = decoder->frameCount();
+        ASSERT_FALSE(decoder->failed());
+        if (frameCount == 0) {
+            truncatedHashes.append(0);
+            continue;
+        }
+        frame = decoder->frameBufferAtIndex(frameCount - 1);
+        if (!frame) {
+            truncatedHashes.append(0);
+            continue;
+        }
+        truncatedHashes.append(hashBitmap(frame->bitmap()));
+    }
+
+    // Compute hashes when the file is progressively decoded.
+    decoder = createDecoder();
+    for (size_t i = 1; i <= fullLength; i += increment) {
+        RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), i);
+        decoder->setData(data.get(), i == fullLength);
+        ASSERT_FALSE(decoder->failed());
+        size_t frameCount = decoder->frameCount();
+        if (frameCount == 0) {
+            progressiveHashes.append(0);
+            continue;
+        }
+        frame = decoder->frameBufferAtIndex(frameCount - 1);
+        if (!frame) {
+            progressiveHashes.append(0);
+            continue;
+        }
+        progressiveHashes.append(hashBitmap(frame->bitmap()));
+    }
+
+    bool match = true;
+    for (size_t i = 0; i < truncatedHashes.size(); ++i) {
+        if (truncatedHashes[i] != progressiveHashes[i]) {
+            match = false;

[scroggo_chromium, 2016/10/25 14:59:06]

Alternatively, could this just be something like

for (...)
  ASSERT_EQ(truncatedHashes[i], progressiveHashes[i]);

+            break;
+        }
+    }
+    EXPECT_TRUE(match);
+
+}
+
+} // Anonymous namespace
+
+// Animated PNG Tests
+
+TEST(AnimatedPNGTests, sizeTest)
+{
+    testSize("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png", IntSize(5, 5));
+    testSize("/LayoutTests/fast/images/resources/png-animated-idat-not-part-of-animation.png", IntSize(227, 35));
+}
+
+TEST(AnimatedPNGTests, repetitionCountTest)
+{
+    testRepetitionCount("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png", 7u);
+    // This is an "animated" image with only one frame, that is, the IDAT is
+    // ignored and there is one fdAT frame. so it should be considered
+    // non-animated.
+    testRepetitionCount("/LayoutTests/fast/images/resources/png-animated-idat-not-part-of-animation.png", cAnimationNone);
+}
+
+// Test if the decoded metdata corresponds to the defined expectations
+TEST(AnimatedPNGTests, MetaDataTest)
+{
+    const char* pngFile = "/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    constexpr size_t expectedFrameCount = 4;
+
+    auto decoder = createDecoderWithPngData(pngFile);
+    ASSERT_EQ(expectedFrameCount, decoder->frameCount());
+    for (size_t i = 0; i < expectedFrameCount; i++)
+        compareFrameWithExpectation(pngAnimatedFrameInfo[i],
+                                    decoder->frameBufferAtIndex(i));
+}
+
+TEST(AnimatedPNGTests, ByteByByteSizeAvailable)
+{
+    testSizeByteByByte("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png",
+                       141u, IntSize(5, 5));
+    testSizeByteByByte("/LayoutTests/fast/images/resources/png-animated-idat-not-part-of-animation.png",
+                       79u, IntSize(227, 35));
+}
+
+// Test whether the frame metadata decoding also works when we provide the data
+// byte by byte. This should cover the case when the client does not provide
+// all data at once. At given offsets, we expect frames to become available.
+// This test checks whether that is the case, and if so, if the frame data is
+// equal to what we expected.
+TEST(AnimatedPNGTests, ByteByByteMetaData)
+{
+    const char* pngFile = "/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    constexpr size_t expectedFrameCount = 4;
+
+    // These are the byte offsets where each frame should have been parsed.
+    // It boils down to the offset of the first fcTL / IEND after the last
+    // frame data chunk, plus 8 bytes for recognition.
+    size_t frameOffsets[expectedFrameCount] = {180, 249, 322, 430};
+
+    auto decoder = createDecoder();
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+    size_t framesParsed = 0;
+
+    for (size_t length = 1; length <= frameOffsets[expectedFrameCount - 1]; length++) {
+        RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(),
+                                                             length);
+        decoder->setData(tempData.get(), false);
+        EXPECT_FALSE(decoder->failed());
+        if (length < frameOffsets[framesParsed]) {
+            EXPECT_EQ(framesParsed, decoder->frameCount());
+        } else {
+            ASSERT_EQ(framesParsed + 1, decoder->frameCount());
+            compareFrameWithExpectation(pngAnimatedFrameInfo[framesParsed],
+                                        decoder->frameBufferAtIndex(framesParsed));
+            framesParsed++;
+        }
+    }
+    EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+    EXPECT_FALSE(decoder->failed());
+}
+
+// This tests if the frame count gets set correctly when parsing frameCount 
+// fails in one of the parsing queries.
+//
+// First, enough data is provided such that two frames should be registered.
+// The decoder should at this point not be in the failed status.
+//
+// Then, we provide the rest of the data except for the last IEND chunk, but
+// tell the decoder that this is all the data we have. Now, the decoder should
+// be in the failed state since all data is provided but no IEND chunk has been
+// seen. The frame count should be three, since one extra frame should be
+// discovered. The fourth frame should *not* be registered since the reader
+// should not be able to determine where the frame ends. 
+TEST(AnimatedPNGTests, FrameCountWithTruncatedData)
+{
+    const char* pngFile = "/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    auto decoder = createDecoder();
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+    
+    // Parse up to and including the first two frames
+    const size_t offsetTwoFrames = 249;
+    const size_t expectedFramesAfter249Bytes = 2;
+    RefPtr<SharedBuffer> tempData = SharedBuffer::create(data->data(),
+                                                         offsetTwoFrames);
+    decoder->setData(tempData.get(), false);
+    EXPECT_EQ(expectedFramesAfter249Bytes, decoder->frameCount());
+    EXPECT_FALSE(decoder->failed());
+    
+    // Provide the rest of the data except for the last IEND chunk.
+    const size_t expectedFramesAfterAllExpect12Bytes = 3;
+    tempData = SharedBuffer::create(data->data(), data->size() - 12);
+    decoder->setData(tempData.get(), true);
+    EXPECT_EQ(expectedFramesAfterAllExpect12Bytes, decoder->frameCount());
+    EXPECT_TRUE(decoder->failed());
+}
+
+TEST(AnimatedPNGTests, TestRandomFrameDecode)
+{
+    RefPtr<SharedBuffer> fullData = readFile("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png");
+    ASSERT_TRUE(fullData.get());
+    Vector<unsigned> baselineHashes;
+    createDecodingBaseline(&createDecoder, fullData.get(), &baselineHashes);
+    size_t frameCount = baselineHashes.size();
+
+    // Random decoding should get the same results as sequential decoding.
+    std::unique_ptr<ImageDecoder> decoder = createDecoder();
+    decoder->setData(fullData.get(), true);
+    const size_t skippingStep = 2;
+    for (size_t i = 0; i < skippingStep; ++i) {
+        for (size_t j = i; j < frameCount; j += skippingStep) {
+            SCOPED_TRACE(testing::Message() << "Random i:" << i << " j:" << j);
+            ImageFrame* frame = decoder->frameBufferAtIndex(j);
+            EXPECT_EQ(baselineHashes[j], hashBitmap(frame->bitmap()));
+        }
+    }
+
+    // Decoding in reverse order.
+    decoder = createDecoder();
+    decoder->setData(fullData.get(), true);
+    for (size_t i = frameCount; i; --i) {
+        SCOPED_TRACE(testing::Message() << "Reverse i:" << i);
+        ImageFrame* frame = decoder->frameBufferAtIndex(i - 1);
+        EXPECT_EQ(baselineHashes[i - 1], hashBitmap(frame->bitmap()));
+    }
+
+}
+
+TEST(AnimatedPNGTests, TestDecodeAfterReallocation)
+{
+    std::unique_ptr<ImageDecoder> decoder = createDecoder();
+    RefPtr<SharedBuffer> data = readFile("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png");
+    ASSERT_TRUE(data.get());
+
+    // Parse from |data|.
+    decoder->setData(data.get(), true);
+    size_t frameCount = decoder->frameCount();
+
+    // ... and then decode frames from |reallocatedData|.

[scroggo_chromium, 2016/10/25 14:59:06]

What is interesting about this test?

(Will PNGImageDecoder even do anything here? Or will it still have the frames
cached?)

[joostouwerling, 2016/10/26 15:44:17]

It should have the frame meta data cached, not the actual frames. It tests
whether decoding still works when supplying data from a different location in
memory, since it does not explicitly parses the stream again. This is a test
that I found in the WebP test suite and I *think* it emulates what's happening
with the DeferredImageDecoder's. My reasoning was here, that if this is a
reasonable scenario for webp, it would also be realistic for apng. 

[scroggo_chromium, 2016/10/26 18:25:58]

Ok, that makes sense. You asked me a question in person about comments I made on
code that was copied from somewhere else. (i.e. should we make changes in
response to my comments in both places?) I think the real answer is we should
consolidate the code. ImageDecoderTestHelpers has a bunch of methods that are
called in multiple tests. If this is the same as in a WEBP test, we should put a
method in that file to share.

[joostouwerling, 2016/10/31 18:40:19]

I will consolidate the tests when this CL is done, or if I have some time
available before that.

+    RefPtr<SharedBuffer> reallocatedData = data.get()->copy();
+    ASSERT_TRUE(reallocatedData.get());
+    data.clear();
+    decoder->setData(reallocatedData.get(), true);
+
+    for (size_t i = 0; i < frameCount; ++i) {
+        const ImageFrame* const frame = decoder->frameBufferAtIndex(i);
+        EXPECT_EQ(ImageFrame::FrameComplete, frame->getStatus());
+    }
+}
+
+TEST(AnimatedPNGTests, ProgressiveDecode)
+{
+    testProgressiveDecoding("/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png");
+}
+
+TEST(AnimatedPNGTests, ParseAndDecodeByteByByte)
+{
+    testByteByByteDecode(&createDecoder,
+                         "/LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png",
+                         4u, 7u);
+}
+
+TEST(AnimatedPNGTests, FctlWrongSizeBreaksDecoding)
+{
+    const char* pngFile = "//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    auto data = readFile(pngFile);
+    ASSERT_FALSE(data->isEmpty());
+
+    // Test the first fcTL in the stream. Because no frame data has been set
+    // at this point, the expected frame count is zero.
+    testInvalidFctlSize("//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png",
+                        95u, 0u);
+    
+    // Test for the third fcTL in the stream. This should be tested as well, 
+    // since the first fcTL is parsed in PNGImageReader::parseSize() whereas
+    // later fcTLs are parsed in PNGImageReader::parse() as part of framecount.
+    // The expected frame count before the fcTL chunk is 1u, since the second
+    // frame is registered when the third fcTL (or IEND) is seen.
+    testInvalidFctlSize("//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png",
+                        241u, 1u);
+
+}
+
+TEST(AnimatedPNGTests, MissingFctlDataBreaksDecoding)
+{
+    // The fcTL chunk starts at 95u, add 10u to get to the content data, and
+    // remove 5 bytes of data.
+    testMissingDataBreaksDecoding(
+        "//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png",
+        105u, 5u);
+}
+
+TEST(AnimatedPNGTests, MissingActlResultsInNonAnimated)
+{
+    const char* pngFile = "//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    auto data = readFile(pngFile);
+    auto decoder = createDecoder();
+    ASSERT_FALSE(data->isEmpty());
+    
+    // Remove the acTL chunk from the stream.
+    size_t offsetActl = 33;
+    RefPtr<SharedBuffer> noActlData = SharedBuffer::create(data->data(),
+                                                            offsetActl);
+    noActlData->append(data->data() + offsetActl + 20,
+                       data->size() - offsetActl - 20);
+
+    decoder->setData(noActlData, true); 
+    EXPECT_EQ(1u, decoder->frameCount());
+    EXPECT_FALSE(decoder->failed());
+}
+
+// Test if the indicated frame count by the acTL is ignored if the actual
+// number of frames is different. Test for higher and lower indicated number.
+TEST(AnimatedPNGTests, differentActlFrameCountIsIgnored)
+{
+    const char* pngFile = "//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    testDifferentActlFrameCountIsIgnored(pngFile, 33u, 2u, 4u);
+    testDifferentActlFrameCountIsIgnored(pngFile, 33u, 8u, 4u);
+}
+
+// Check if a frame rectangle, that is larger than the image width, gets
+// clipped correctly.
+TEST(AnimatedPNGTests, frameRectIsClipped)
+{
+    const char* pngFile = "//LayoutTests/fast/images/resources/png-animated-idat-part-of-animation.png";
+    auto data = readFile(pngFile);
+    auto decoder = createDecoder();
+    ASSERT_FALSE(data->isEmpty());
+    
+    // Change the width and height of the frame so it falls outside the image.
+    size_t offsetThirdFctl = 241 + 12;
+    RefPtr<SharedBuffer> modifiedData = SharedBuffer::create(data->data(),
+                                                             offsetThirdFctl);
+    png_byte sizeChunk[8];
+    writeUint32(10, sizeChunk);
+    writeUint32(15, sizeChunk + 4);
+    modifiedData->append(const_cast<const char*>(
+                            reinterpret_cast<char*>(sizeChunk)), 8u);
+    modifiedData->append(data->data() + offsetThirdFctl + 8,
+                         data->size() - offsetThirdFctl - 8);
+
+    decoder->setData(modifiedData, true); 
+
+    IntSize expectedSize(5, 5);
+    size_t expectedFrameCount = 4;
+    IntRect expectedFrameRect(IntPoint(1, 2), IntSize(4, 3));
+
+    EXPECT_TRUE(decoder->isSizeAvailable());
+    EXPECT_EQ(expectedSize, decoder->size());
+    EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+    ASSERT_FALSE(decoder->failed());
+    EXPECT_EQ(expectedFrameRect,
+              decoder->frameBufferAtIndex(2)->originalFrameRect());
+    
+}
+
+// Static PNG tests
+
+TEST(StaticPNGTests, repetitionCountTest)
+{
+    testRepetitionCount("/LayoutTests/fast/images/resources/png-simple.png",
+                        cAnimationNone);
+}
+
+TEST(StaticPNGTests, sizeTest)
+{
+    testSize("/LayoutTests/fast/images/resources/png-simple.png",
+             IntSize(111, 29));
+}
+
+TEST(StaticPNGTests, MetaDataTest)
+{
+    const size_t expectedFrameCount = 1;
+    const size_t expectedDuration = 0;
+    auto decoder = createDecoderWithPngData("/LayoutTests/fast/images/resources/png-simple.png");
+    EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+    EXPECT_EQ(expectedDuration, decoder->frameDurationAtIndex(0));
+}
+
+// This test removes two random byets from the IHDR chunk. The decoder should
+// fail on this since all IHDR data is necessary to decode a PNG image.
+TEST(StaticPNGTests, InvalidIHDRChunk)
+{
+    testMissingDataBreaksDecoding(
+        "//LayoutTests/fast/images/resources/png-simple.png", 20u, 2u);
+} 
+
+TEST(StaticPNGTests, ProgressiveDecoding)
+{
+    testProgressiveDecoding("/LayoutTests/fast/images/resources/png-simple.png");
+}
+
+}; // namespace blink