Add support for Animated PNG

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
index 5281c1ba065c9005ab9e27924de31e316852d74c..9ffe4d4768fb70eb65c3f47e88fd372f5c0b7175 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoderTest.cpp
@@ -4,9 +4,28 @@
 
 #include "platform/image-decoders/png/PNGImageDecoder.h"
 
+#include <memory>
 #include "platform/image-decoders/ImageDecoderTestHelpers.h"
+#include "png.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include <memory>
+
+// /LayoutTests/images/resources/png-animated-idat-part-of-animation.png
+// is modified in multiple tests to simulate erroneous PNGs. As a reference,
+// the table below shows how the file is structured.
+//
+// Offset | 8     33    95    133   172   210   241   279   314   352   422
+// -------------------------------------------------------------------------
+// Chunk  | IHDR  acTL  fcTL  IDAT  fcTL  fdAT  fcTL  fdAT  fcTL  fdAT  IEND
+//
+// In between the acTL and fcTL there are two other chunks, PLTE and tRNS, but
+// those are not specifically used in this test suite. The same holds for a
+// tEXT chunk in between the last fdAT and IEND.
+//
+// In the current behavior of PNG image decoders, the 4 frames are detected when
+// respectively 141, 249, 322 and 430 bytes are received. The first frame should
+// be detected when the IDAT has been received, and non-first frames when the
+// next fcTL or IEND chunk has been received. Note that all offsets are +8,
+// because a chunk is identified by byte 4-7.
 
 namespace blink {
 
@@ -37,21 +56,170 @@ void testSize(const char* pngFile, IntSize expectedSize) {
   EXPECT_EQ(expectedSize, decoder->size());
 }
 
+// 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());
+
+  const char* source = data->data();
+  RefPtr<SharedBuffer> partialData = SharedBuffer::create();
+  for (size_t length = 1; length <= bytesNeededToDecodeSize; length++) {
+    partialData->append(source++, 1u);
+    decoder->setData(partialData.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());
+}
+
+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);
-  // Decoding the frame count sets the repetition count as well.
+  // Decoding the frame count sets the number of repetitions as well.
   decoder->frameCount();
   EXPECT_FALSE(decoder->failed());
   EXPECT_EQ(expectedRepetitionCount, decoder->repetitionCount());
 }
 
+struct PublicFrameInfo {
+  size_t duration;
+  IntRect frameRect;
+  ImageFrame::AlphaBlendSource alphaBlend;
+  ImageFrame::DisposalMethod disposalMethod;
+};
+
+// This is the frame data for the following PNG image:
+// /LayoutTests/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,
+                                 ImageDecoder* decoder,
+                                 size_t index) {
+  EXPECT_EQ(expected.duration, decoder->frameDurationAtIndex(index));
+
+  const auto* frame = decoder->frameBufferAtIndex(index);
+  ASSERT_TRUE(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 result in a failed decode because the
+// parser jumps |length| bytes too far in the next chunk.
+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(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());
+}
+
+// Verify that a decoder with a parse error converts to a static image.
+static void expectStatic(ImageDecoder* decoder) {
+  EXPECT_EQ(1u, decoder->frameCount());
+  EXPECT_FALSE(decoder->failed());
+
+  ImageFrame* frame = decoder->frameBufferAtIndex(0);
+  ASSERT_NE(nullptr, frame);
+  EXPECT_EQ(ImageFrame::FrameComplete, frame->getStatus());
+  EXPECT_FALSE(decoder->failed());
+  EXPECT_EQ(cAnimationNone, decoder->repetitionCount());
+}
+
+// Decode up to the indicated fcTL offset and then provide an fcTL with the
+// wrong chunk size (20 instead of 26).
+void testInvalidFctlSize(const char* pngFile,
+                         size_t offsetFctl,
+                         size_t expectedFrameCount,
+                         bool shouldFail) {
+  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(expectedFrameCount, decoder->frameCount());
+  ASSERT_FALSE(decoder->failed());
+
+  // Append the wrong size to the data stream
+  png_byte sizeChunk[4];
+  writeUint32(20, sizeChunk);
+  invalidData->append(reinterpret_cast<char*>(sizeChunk), 4u);
+
+  // Skip the size in the original data, but provide a truncated fcTL,
+  // which is 4B of tag, 20B of data and 4B of CRC, totalling 28B.
+  invalidData->append(data->data() + offsetFctl + 4, 28u);
+  // Append the rest of the data
+  const size_t offsetPostFctl = offsetFctl + 38;
+  invalidData->append(data->data() + offsetPostFctl,
+                      data->size() - offsetPostFctl);
+
+  decoder->setData(invalidData, false);
+  if (shouldFail) {
+    EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+    EXPECT_EQ(true, decoder->failed());
+  } else {
+    expectStatic(decoder.get());
+  }
+}
+
 // Verify that the decoder can successfully decode the first frame when
 // initially only half of the frame data is received, resulting in a partially
 // decoded image, and then the rest of the image data is received. Verify that
 // the bitmap hashes of the two stages are different. Also verify that the final
 // bitmap hash is equivalent to the hash when all data is provided at once.
 //
-// This verifies that decoder correctly keeps track of where it stopped
+// This verifies that the decoder correctly keeps track of where it stopped
 // decoding when the image was not yet fully received.
 void testProgressiveDecodingContinuesAfterFullData(const char* pngFile,
                                                    size_t offsetMidFirstFrame) {
@@ -60,7 +228,7 @@ void testProgressiveDecodingContinuesAfterFullData(const char* pngFile,
 
   auto decoderUpfront = createDecoder();
   decoderUpfront->setData(fullData.get(), true);
-  EXPECT_GE(1u, decoderUpfront->frameCount());
+  EXPECT_GE(decoderUpfront->frameCount(), 1u);
   const ImageFrame* const frameUpfront = decoderUpfront->frameBufferAtIndex(0);
   ASSERT_EQ(ImageFrame::FrameComplete, frameUpfront->getStatus());
   const unsigned hashUpfront = hashBitmap(frameUpfront->bitmap());
@@ -86,16 +254,11 @@ void testProgressiveDecodingContinuesAfterFullData(const char* pngFile,
 }
 
 // Modify the frame data bytes for frame |frameIndex| so that decoding fails.
-// Parsing should work fine, and is checked with |expectedFrameCountBefore|. If
-// the failure should invalidate the decoder, |expectFailure| should be set to
-// true. If not, |expectedFrameCountAfter| should indicate the new frame count
-// after the failure.
+// Parsing should work fine, and is checked with |expectedFrameCount|.
 void testFailureDuringDecode(const char* file,
                              size_t idatOffset,
                              size_t frameIndex,
-                             bool expectFailure,
-                             size_t expectedFrameCountBefore,
-                             size_t expectedFrameCountAfter = 0u) {
+                             size_t expectedFrameCount) {
   RefPtr<SharedBuffer> fullData = readFile(file);
   ASSERT_FALSE(fullData->isEmpty());
 
@@ -112,18 +275,664 @@ void testFailureDuringDecode(const char* file,
   auto decoder = createDecoder();
   decoder->setData(data.get(), true);
 
-  EXPECT_EQ(expectedFrameCountBefore, decoder->frameCount());
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+
+  decoder->frameBufferAtIndex(frameIndex);
+  ASSERT_EQ(true, decoder->failed());
 
-  const ImageFrame* const frame = decoder->frameBufferAtIndex(frameIndex);
-  EXPECT_EQ(expectFailure, decoder->failed());
-  if (!expectFailure) {
-    EXPECT_EQ(expectedFrameCountAfter, decoder->frameCount());
-    EXPECT_EQ(ImageFrame::FrameEmpty, frame->getStatus());
-  }
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
 }
 
 }  // Anonymous namespace
 
+// Animated PNG Tests
+
+TEST(AnimatedPNGTests, sizeTest) {
+  testSize(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      IntSize(5, 5));
+  testSize(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-not-part-of-animation.png",
+      IntSize(227, 35));
+}
+
+TEST(AnimatedPNGTests, repetitionCountTest) {
+  testRepetitionCount(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      6u);
+  // 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/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/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.get(), i);
+  }
+}
+
+TEST(AnimatedPNGTests, EmptyFrame) {
+  const char* pngFile = "/LayoutTests/images/resources/empty-frame.png";
+  auto decoder = createDecoderWithPngData(pngFile);
+  // Frame 0 is empty. Ensure that decoding frame 1 (which depends on frame 0)
+  // fails (rather than crashing).
+  EXPECT_EQ(2u, decoder->frameCount());
+  EXPECT_FALSE(decoder->failed());
+
+  ImageFrame* frame = decoder->frameBufferAtIndex(1);
+  EXPECT_TRUE(decoder->failed());
+  ASSERT_NE(nullptr, frame);
+  EXPECT_EQ(ImageFrame::FrameEmpty, frame->getStatus());
+}
+
+TEST(AnimatedPNGTests, ByteByByteSizeAvailable) {
+  testSizeByteByByte(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      141u, IntSize(5, 5));
+  testSizeByteByByte(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-not-part-of-animation.png",
+      79u, IntSize(227, 35));
+}
+
+TEST(AnimatedPNGTests, ByteByByteMetaData) {
+  const char* pngFile =
+      "/LayoutTests/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. The exception on this is
+  // the first frame, which is reported when its first framedata is seen.
+  size_t frameOffsets[expectedFrameCount] = {141, 249, 322, 430};
+
+  auto decoder = createDecoder();
+  auto data = readFile(pngFile);
+  ASSERT_FALSE(data->isEmpty());
+  size_t framesParsed = 0;
+
+  const char* source = data->data();
+  RefPtr<SharedBuffer> partialData = SharedBuffer::create();
+  for (size_t length = 1; length <= frameOffsets[expectedFrameCount - 1];
+       length++) {
+    partialData->append(source++, 1u);
+    decoder->setData(partialData.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.get(), framesParsed);
+      framesParsed++;
+    }
+  }
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+  EXPECT_FALSE(decoder->failed());
+}
+
+TEST(AnimatedPNGTests, TestRandomFrameDecode) {
+  testRandomFrameDecode(&createDecoder,
+                        "/LayoutTests/images/resources/"
+                        "png-animated-idat-part-of-animation.png",
+                        2u);
+}
+
+TEST(AnimatedPNGTests, TestDecodeAfterReallocation) {
+  testDecodeAfterReallocatingData(&createDecoder,
+                                  "/LayoutTests/images/resources/"
+                                  "png-animated-idat-part-of-animation.png");
+}
+
+TEST(AnimatedPNGTests, ProgressiveDecode) {
+  testProgressiveDecoding(&createDecoder,
+                          "/LayoutTests/images/resources/"
+                          "png-animated-idat-part-of-animation.png",
+                          13u);
+}
+
+TEST(AnimatedPNGTests, ParseAndDecodeByteByByte) {
+  testByteByByteDecode(&createDecoder,
+                       "/LayoutTests/images/resources/"
+                       "png-animated-idat-part-of-animation.png",
+                       4u, 6u);
+}
+
+TEST(AnimatedPNGTests, FailureDuringParsing) {
+  // Test the first fcTL in the stream. Because no frame data has been set at
+  // this point, the expected frame count is zero. 95 bytes is just before the
+  // first fcTL chunk, at which the first frame is detected. This is before the
+  // IDAT, so it should be treated as a static image.
+  testInvalidFctlSize(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      95u, 0u, false);
+
+  // Test for the third fcTL in the stream. This should see 1 frame before the
+  // fcTL, and then fail when parsing it.
+  testInvalidFctlSize(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      241u, 1u, true);
+}
+
+TEST(AnimatedPNGTests, ActlErrors) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  auto data = readFile(pngFile);
+  ASSERT_FALSE(data->isEmpty());
+
+  const size_t offsetActl = 33u;
+  const size_t acTLSize = 20u;
+  {
+    // Remove the acTL chunk from the stream. This results in a static image.
+    RefPtr<SharedBuffer> noActlData =
+        SharedBuffer::create(data->data(), offsetActl);
+    noActlData->append(data->data() + offsetActl + acTLSize,
+                       data->size() - offsetActl - acTLSize);
+
+    auto decoder = createDecoder();
+    decoder->setData(noActlData, true);
+    EXPECT_EQ(1u, decoder->frameCount());
+    EXPECT_FALSE(decoder->failed());
+    EXPECT_EQ(cAnimationNone, decoder->repetitionCount());
+  }
+
+  // Store the acTL for more tests.
+  char acTL[acTLSize];
+  memcpy(acTL, data->data() + offsetActl, acTLSize);
+
+  // Insert an extra acTL at a couple of different offsets.
+  // Prior to the IDAT, this should result in a static image. After, this
+  // should fail.
+  const struct {
+    size_t offset;
+    bool shouldFail;
+  } gRecs[] = {{8u, false},
+               {offsetActl, false},
+               {133u, false},
+               {172u, true},
+               {422u, true}};
+  for (const auto& rec : gRecs) {
+    const size_t offset = rec.offset;
+    RefPtr<SharedBuffer> extraActlData =
+        SharedBuffer::create(data->data(), offset);
+    extraActlData->append(acTL, acTLSize);
+    extraActlData->append(data->data() + offset, data->size() - offset);
+    auto decoder = createDecoder();
+    decoder->setData(extraActlData, true);
+    EXPECT_EQ(rec.shouldFail ? 0u : 1u, decoder->frameCount());
+    EXPECT_EQ(rec.shouldFail, decoder->failed());
+  }
+
+  // An acTL after IDAT is ignored.
+  pngFile =
+      "/LayoutTests/images/resources/"
+      "cHRM_color_spin.png";
+  {
+    auto data2 = readFile(pngFile);
+    ASSERT_FALSE(data2->isEmpty());
+    const size_t postIDATOffset = 30971u;
+    for (size_t times = 0; times < 2; times++) {
+      RefPtr<SharedBuffer> extraActlData =
+          SharedBuffer::create(data2->data(), postIDATOffset);
+      for (size_t i = 0; i < times; i++)
+        extraActlData->append(acTL, acTLSize);
+      extraActlData->append(data2->data() + postIDATOffset,
+                            data2->size() - postIDATOffset);
+
+      auto decoder = createDecoder();
+      decoder->setData(extraActlData, true);
+      EXPECT_EQ(1u, decoder->frameCount());
+      EXPECT_FALSE(decoder->failed());
+      EXPECT_EQ(cAnimationNone, decoder->repetitionCount());
+      EXPECT_NE(nullptr, decoder->frameBufferAtIndex(0));
+      EXPECT_FALSE(decoder->failed());
+    }
+  }
+}
+
+TEST(AnimatedPNGTests, fdatBeforeIdat) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-not-part-of-animation.png";
+  auto data = readFile(pngFile);
+  ASSERT_FALSE(data->isEmpty());
+
+  // Insert fcTL and fdAT prior to the IDAT
+  const size_t idatOffset = 71u;
+  RefPtr<SharedBuffer> modifiedData =
+      SharedBuffer::create(data->data(), idatOffset);
+  // Copy fcTL and fdAT
+  const size_t fctlPlusFdatSize = 38u + 1566u;
+  modifiedData->append(data->data() + 2519u, fctlPlusFdatSize);
+  // Copy IDAT
+  modifiedData->append(data->data() + idatOffset, 2448u);
+  // Copy the remaining
+  modifiedData->append(data->data() + 4123u, 39u + 12u);
+  // Data has just been rearranged.
+  ASSERT_EQ(data->size(), modifiedData->size());
+
+  {
+    // This broken APNG will be treated as a static png.
+    auto decoder = createDecoder();
+    decoder->setData(modifiedData.get(), true);
+    expectStatic(decoder.get());
+  }
+
+  {
+    // Remove the acTL from the modified image. It now has fdAT before
+    // IDAT, but no acTL, so fdAT should be ignored.
+    const size_t offsetActl = 33u;
+    const size_t acTLSize = 20u;
+    RefPtr<SharedBuffer> modifiedData2 =
+        SharedBuffer::create(modifiedData->data(), offsetActl);
+    modifiedData2->append(modifiedData->data() + offsetActl + acTLSize,
+                          modifiedData->size() - offsetActl);
+    auto decoder = createDecoder();
+    decoder->setData(modifiedData2.get(), true);
+    expectStatic(decoder.get());
+
+    // Likewise, if an acTL follows the fdAT, it is ignored.
+    const size_t insertionOffset = idatOffset + fctlPlusFdatSize - acTLSize;
+    RefPtr<SharedBuffer> modifiedData3 =
+        SharedBuffer::create(modifiedData2->data(), insertionOffset);
+    modifiedData3->append(data->data() + offsetActl, acTLSize);
+    modifiedData3->append(modifiedData2->data() + insertionOffset,
+                          modifiedData2->size() - insertionOffset);
+    decoder = createDecoder();
+    decoder->setData(modifiedData3.get(), true);
+    expectStatic(decoder.get());
+  }
+}
+
+TEST(AnimatedPNGTests, IdatSizeMismatch) {
+  // The default image must fill the image
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  auto data = readFile(pngFile);
+  ASSERT_FALSE(data->isEmpty());
+
+  const size_t fctlOffset = 95u;
+  RefPtr<SharedBuffer> modifiedData =
+      SharedBuffer::create(data->data(), fctlOffset);
+  const size_t fctlSize = 38u;
+  png_byte fctl[fctlSize];
+  memcpy(fctl, data->data() + fctlOffset, fctlSize);
+  // Set the height to a smaller value, so it does not fill the image.
+  writeUint32(3, fctl + 16);
+  // Correct the crc
+  writeUint32(3210324191, fctl + 34);
+  modifiedData->append((const char*)fctl, fctlSize);
+  const size_t afterFctl = fctlOffset + fctlSize;
+  modifiedData->append(data->data() + afterFctl, data->size() - afterFctl);
+
+  auto decoder = createDecoder();
+  decoder->setData(modifiedData.get(), true);
+  expectStatic(decoder.get());
+}
+
+// Originally, the third frame has an offset of (1,2) and a size of (3,2). By
+// changing the offset to (4,4), the frame rect is no longer within the image
+// size of 5x5. This results in a failure.
+TEST(AnimatedPNGTests, VerifyFrameOutsideImageSizeFails) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  auto data = readFile(pngFile);
+  auto decoder = createDecoder();
+  ASSERT_FALSE(data->isEmpty());
+
+  const size_t offsetThirdFctl = 241;
+  RefPtr<SharedBuffer> modifiedData =
+      SharedBuffer::create(data->data(), offsetThirdFctl);
+  const size_t fctlSize = 38u;
+  png_byte fctl[fctlSize];
+  memcpy(fctl, data->data() + offsetThirdFctl, fctlSize);
+  // Modify offset and crc.
+  writeUint32(4, fctl + 20u);
+  writeUint32(4, fctl + 24u);
+  writeUint32(3700322018, fctl + 34u);
+
+  modifiedData->append(const_cast<const char*>(reinterpret_cast<char*>(fctl)),
+                       fctlSize);
+  modifiedData->append(data->data() + offsetThirdFctl + fctlSize,
+                       data->size() - offsetThirdFctl - fctlSize);
+
+  decoder->setData(modifiedData, true);
+
+  IntSize expectedSize(5, 5);
+  EXPECT_TRUE(decoder->isSizeAvailable());
+  EXPECT_EQ(expectedSize, decoder->size());
+
+  const size_t expectedFrameCount = 0;
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+  EXPECT_TRUE(decoder->failed());
+}
+
+TEST(AnimatedPNGTests, ProgressiveDecodingContinuesAfterFullData) {
+  // 160u is a randomly chosen offset in the IDAT chunk of the first frame.
+  testProgressiveDecodingContinuesAfterFullData(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      160u);
+}
+
+TEST(AnimatedPNGTests, RandomDecodeAfterClearFrameBufferCache) {
+  testRandomDecodeAfterClearFrameBufferCache(
+      &createDecoder,
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      2u);
+}
+
+TEST(AnimatedPNGTests, VerifyAlphaBlending) {
+  testAlphaBlending(&createDecoder,
+                    "/LayoutTests/images/resources/"
+                    "png-animated-idat-part-of-animation.png");
+}
+
+// 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.  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. The decoder should *not* be in the failed state since
+// there are three frames which can be shown.
+// Attempting to decode the third frame should fail, since the file is
+// truncated.
+TEST(AnimatedPNGTests, FailureMissingIendChunk) {
+  RefPtr<SharedBuffer> fullData = readFile(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png");
+  ASSERT_FALSE(fullData->isEmpty());
+  auto decoder = createDecoder();
+
+  const size_t offsetTwoFrames = 249;
+  const size_t expectedFramesAfter249Bytes = 2;
+  RefPtr<SharedBuffer> tempData =
+      SharedBuffer::create(fullData->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 expectedFramesAfterAllExcept12Bytes = 3;
+  tempData = SharedBuffer::create(fullData->data(), fullData->size() - 12);
+  decoder->setData(tempData.get(), true);
+  ASSERT_EQ(expectedFramesAfterAllExcept12Bytes, decoder->frameCount());
+
+  for (size_t i = 0; i < expectedFramesAfterAllExcept12Bytes; i++) {
+    EXPECT_FALSE(decoder->failed());
+    decoder->frameBufferAtIndex(i);
+  }
+
+  EXPECT_TRUE(decoder->failed());
+}
+
+TEST(AnimatedPNGTests, FailureDuringDecodingInvalidatesDecoder) {
+  testFailureDuringDecode(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      291u,  // fdat offset for frame index 2, plus 12 to move past sequence
+             // number.
+      2u,    // try to decode frame index 2
+      4u);   // expected frame count before failure
+
+  testFailureDuringDecode(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png",
+      133u,  // idat offset for frame index 0
+      0u,    // try to decode frame index 0
+      4u);   // expected frame count before failure
+}
+
+// Verify that a malformatted PNG, where the IEND appears before any frame data
+// (IDAT), invalidates the decoder.
+TEST(AnimatedPNGTests, VerifyIENDBeforeIDATInvalidatesDecoder) {
+  RefPtr<SharedBuffer> fullData = readFile(
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png");
+  ASSERT_FALSE(fullData->isEmpty());
+  auto decoder = createDecoder();
+
+  const size_t offsetIDAT = 133;
+  RefPtr<SharedBuffer> data =
+      SharedBuffer::create(fullData->data(), offsetIDAT);
+  data->append(fullData->data() + fullData->size() - 12u, 12u);
+  data->append(fullData->data() + offsetIDAT, fullData->size() - offsetIDAT);
+  decoder->setData(data.get(), true);
+
+  const size_t expectedFrameCount = 0u;
+  EXPECT_EQ(expectedFrameCount, decoder->frameCount());
+  EXPECT_TRUE(decoder->failed());
+}
+
+// All IDAT chunks must be before all fdAT chunks
+TEST(AnimatedPNGTests, MixedDataChunks) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  RefPtr<SharedBuffer> fullData = readFile(pngFile);
+  ASSERT_FALSE(fullData->isEmpty());
+
+  // Add an extra fdAT after the first IDAT, skipping fcTL.
+  const size_t postIDAT = 172u;
+  RefPtr<SharedBuffer> data = SharedBuffer::create(fullData->data(), postIDAT);
+  const size_t fcTLSize = 38u;
+  const size_t fdATSize = 31u;
+  png_byte fdAT[fdATSize];
+  memcpy(fdAT, fullData->data() + postIDAT + fcTLSize, fdATSize);
+  // Modify the sequence number
+  writeUint32(1u, fdAT + 8);
+  data->append((const char*)fdAT, fdATSize);
+  const size_t IENDOffset = 422u;
+  data->append(fullData->data() + IENDOffset, fullData->size() - IENDOffset);
+  auto decoder = createDecoder();
+  decoder->setData(data.get(), true);
+  decoder->frameCount();
+  EXPECT_TRUE(decoder->failed());
+
+  // Insert an IDAT after an fdAT.
+  const size_t postfdAT = postIDAT + fcTLSize + fdATSize;
+  data = SharedBuffer::create(fullData->data(), postfdAT);
+  const size_t IDATOffset = 133u;
+  data->append(fullData->data() + IDATOffset, postIDAT - IDATOffset);
+  // Append the rest.
+  data->append(fullData->data() + postIDAT, fullData->size() - postIDAT);
+  decoder = createDecoder();
+  decoder->setData(data.get(), true);
+  decoder->frameCount();
+  EXPECT_TRUE(decoder->failed());
+}
+
+// Verify that erroneous values for the disposal method and alpha blending
+// cause the decoder to fail.
+TEST(AnimatedPNGTests, VerifyInvalidDisposalAndBlending) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  RefPtr<SharedBuffer> fullData = readFile(pngFile);
+  ASSERT_FALSE(fullData->isEmpty());
+  auto decoder = createDecoder();
+
+  // The disposal byte in the frame control chunk is the 24th byte, alpha
+  // blending the 25th. |offsetDisposalOp| is 241 bytes to get to the third
+  // fctl chunk, 8 bytes to skip the length and tag bytes, and 24 bytes to get
+  // to the disposal op.
+  //
+  // Write invalid values to the disposal and alpha blending byte, correct the
+  // crc and append the rest of the buffer.
+  const size_t offsetDisposalOp = 241 + 8 + 24;
+  RefPtr<SharedBuffer> data =
+      SharedBuffer::create(fullData->data(), offsetDisposalOp);
+  png_byte disposalAndBlending[6u];
+  disposalAndBlending[0] = 7;
+  disposalAndBlending[1] = 9;
+  writeUint32(2408835439u, disposalAndBlending + 2u);
+  data->append(reinterpret_cast<char*>(disposalAndBlending), 6u);
+  data->append(fullData->data() + offsetDisposalOp + 6u,
+               fullData->size() - offsetDisposalOp - 6u);
+
+  decoder->setData(data.get(), true);
+  decoder->frameCount();
+  ASSERT_TRUE(decoder->failed());
+}
+
+// This test verifies that the following situation does not invalidate the
+// decoder:
+// - Frame 0 is decoded progressively, but there's not enough data to fully
+//   decode it.
+// - The rest of the image data is received.
+// - Frame X, with X > 0, and X does not depend on frame 0, is decoded.
+// - Frame 0 is decoded.
+// This is a tricky case since the decoder resets the png struct for each frame,
+// and this test verifies that it does not break the decoding of frame 0, even
+// though it already started in the first call.
+TEST(AnimatedPNGTests, VerifySuccessfulFirstFrameDecodeAfterLaterFrame) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-three-independent-frames.png";
+  auto decoder = createDecoder();
+  auto fullData = readFile(pngFile);
+  ASSERT_FALSE(fullData->isEmpty());
+
+  // 160u is a randomly chosen offset in the IDAT chunk of the first frame.
+  const size_t middleFirstFrame = 160u;
+  RefPtr<SharedBuffer> data =
+      SharedBuffer::create(fullData->data(), middleFirstFrame);
+  decoder->setData(data.get(), false);
+
+  ASSERT_EQ(1u, decoder->frameCount());
+  ASSERT_EQ(ImageFrame::FramePartial,
+            decoder->frameBufferAtIndex(0)->getStatus());
+
+  decoder->setData(fullData.get(), true);
+  ASSERT_EQ(3u, decoder->frameCount());
+  ASSERT_EQ(ImageFrame::FrameComplete,
+            decoder->frameBufferAtIndex(1)->getStatus());
+  // The point is that this call does not decode frame 0, which it won't do if
+  // it does not have it as its required previous frame.
+  ASSERT_EQ(kNotFound,
+            decoder->frameBufferAtIndex(1)->requiredPreviousFrameIndex());
+
+  EXPECT_EQ(ImageFrame::FrameComplete,
+            decoder->frameBufferAtIndex(0)->getStatus());
+  EXPECT_FALSE(decoder->failed());
+}
+
+// If the decoder attempts to decode a non-first frame which is subset and
+// independent, it needs to discard its png_struct so it can use a modified
+// IHDR. Test this by comparing a decode of frame 1 after frame 0 to a decode
+// of frame 1 without decoding frame 0.
+TEST(AnimatedPNGTests, DecodeFromIndependentFrame) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-part-of-animation.png";
+  auto originalData = readFile(pngFile);
+  ASSERT_FALSE(originalData->isEmpty());
+
+  // This file almost fits the bill. Modify it to dispose frame 0, making
+  // frame 1 independent.
+  const size_t kDisposeOffset = 127u;
+  auto data = SharedBuffer::create(originalData->data(), kDisposeOffset);
+  // 1 Corresponds to APNG_DISPOSE_OP_BACKGROUND
+  const char one = '\001';
+  data->append(&one, 1u);
+  // No need to modify the blend op
+  data->append(originalData->data() + kDisposeOffset + 1, 1u);
+  // Modify the CRC
+  png_byte crc[4];
+  writeUint32(2226670956, crc);
+  data->append(reinterpret_cast<const char*>(crc), 4u);
+  data->append(originalData->data() + data->size(),
+               originalData->size() - data->size());
+  ASSERT_EQ(originalData->size(), data->size());
+
+  auto decoder = createDecoder();
+  decoder->setData(data.get(), true);
+
+  ASSERT_EQ(4u, decoder->frameCount());
+  ASSERT_FALSE(decoder->failed());
+
+  auto* frame = decoder->frameBufferAtIndex(0);
+  ASSERT_TRUE(frame);
+  ASSERT_EQ(ImageFrame::DisposeOverwriteBgcolor, frame->getDisposalMethod());
+
+  frame = decoder->frameBufferAtIndex(1);
+  ASSERT_TRUE(frame);
+  ASSERT_FALSE(decoder->failed());
+  ASSERT_NE(IntRect({}, decoder->size()), frame->originalFrameRect());
+  ASSERT_EQ(kNotFound, frame->requiredPreviousFrameIndex());
+
+  const auto hash = hashBitmap(frame->bitmap());
+
+  // Now decode starting from frame 1.
+  decoder = createDecoder();
+  decoder->setData(data.get(), true);
+
+  frame = decoder->frameBufferAtIndex(1);
+  ASSERT_TRUE(frame);
+  EXPECT_EQ(hash, hashBitmap(frame->bitmap()));
+}
+
+// If the first frame is subset from IHDR (only allowed if the first frame is
+// not the default image), the decoder has to destroy the png_struct it used
+// for parsing so it can use a modified IHDR.
+TEST(AnimatedPNGTests, SubsetFromIHDR) {
+  const char* pngFile =
+      "/LayoutTests/images/resources/"
+      "png-animated-idat-not-part-of-animation.png";
+  auto originalData = readFile(pngFile);
+  ASSERT_FALSE(originalData->isEmpty());
+
+  const size_t fcTLOffset = 2519u;
+  auto data = SharedBuffer::create(originalData->data(), fcTLOffset);
+
+  const size_t fcTLSize = 38u;
+  png_byte fcTL[fcTLSize];
+  memcpy(fcTL, originalData->data() + fcTLOffset, fcTLSize);
+  // Modify to have a subset frame (yOffset 1, height 34 out of 35).
+  writeUint32(34, fcTL + 16u);
+  writeUint32(1, fcTL + 24u);
+  writeUint32(3972842751, fcTL + 34u);
+  data->append(reinterpret_cast<const char*>(fcTL), fcTLSize);
+
+  // Append the rest of the data.
+  // Note: If PNGImageDecoder changes to reject an image with too many
+  // rows, the fdAT data will need to be modified as well.
+  data->append(originalData->data() + fcTLOffset + fcTLSize,
+               originalData->size() - data->size());
+  ASSERT_EQ(originalData->size(), data->size());
+
+  // This will test both byte by byte and using the full data, and compare.
+  testByteByByteDecode(createDecoder, data.get(), 1, cAnimationNone);
+}
+
 // Static PNG tests
 
 TEST(StaticPNGTests, repetitionCountTest) {
@@ -144,6 +953,11 @@ TEST(StaticPNGTests, MetaDataTest) {
   EXPECT_EQ(expectedDuration, decoder->frameDurationAtIndex(0));
 }
 
+TEST(StaticPNGTests, InvalidIHDRChunk) {
+  testMissingDataBreaksDecoding("/LayoutTests/images/resources/png-simple.png",
+                                20u, 2u);
+}
+
 TEST(StaticPNGTests, ProgressiveDecoding) {
   testProgressiveDecoding(&createDecoder,
                           "/LayoutTests/images/resources/png-simple.png", 11u);
@@ -159,20 +973,74 @@ TEST(StaticPNGTests, FailureDuringDecodingInvalidatesDecoder) {
       "/LayoutTests/images/resources/png-simple.png",
       85u,   // idat offset for frame index 0
       0u,    // try to decode frame index 0
-      true,  // expect the decoder to be invalidated after the failure
       1u);   // expected frame count before failure
 }
 
-// For static images, frameIsCompleteAtIndex(0) should return true if and only
-// if the frame is successfully decoded, not when it is fully received.
-TEST(StaticPNGTests, VerifyFrameCompleteBehavior) {
-  auto decoder =
-      createDecoderWithPngData("/LayoutTests/images/resources/png-simple.png");
-  EXPECT_EQ(1u, decoder->frameCount());
-  EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
-  EXPECT_EQ(ImageFrame::FrameComplete,
-            decoder->frameBufferAtIndex(0)->getStatus());
-  EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
+TEST(PNGTests, VerifyFrameCompleteBehavior) {
+  struct {
+    const char* name;
+    size_t expectedFrameCount;
+    size_t offsetInFirstFrame;
+  } gRecs[] = {
+      {"/LayoutTests/images/resources/"
+       "png-animated-three-independent-frames.png",
+       3u, 150u},
+      {"/LayoutTests/images/resources/"
+       "png-animated-idat-part-of-animation.png",
+       4u, 160u},
+
+      {"/LayoutTests/images/resources/png-simple.png", 1u, 700u},
+      {"/LayoutTests/images/resources/lenna.png", 1u, 40000u},
+  };
+  for (const auto& rec : gRecs) {
+    auto fullData = readFile(rec.name);
+    ASSERT_TRUE(fullData.get());
+
+    // Create with enough data for part of the first frame.
+    auto decoder = createDecoder();
+    auto data = SharedBuffer::create(fullData->data(), rec.offsetInFirstFrame);
+    decoder->setData(data.get(), false);
+
+    EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+
+    // Parsing the size is not enough to mark the frame as complete.
+    EXPECT_TRUE(decoder->isSizeAvailable());
+    EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+
+    const auto partialFrameCount = decoder->frameCount();
+    EXPECT_EQ(1u, partialFrameCount);
+
+    // Frame is not complete, even after decoding partially.
+    EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+    auto* frame = decoder->frameBufferAtIndex(0);
+    ASSERT_TRUE(frame);
+    EXPECT_NE(ImageFrame::FrameComplete, frame->getStatus());
+    EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+
+    decoder->setData(fullData.get(), true);
+
+    // With full data, parsing the size still does not mark a frame as
+    // complete.
+    EXPECT_TRUE(decoder->isSizeAvailable());
+    EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+
+    const auto frameCount = decoder->frameCount();
+    ASSERT_EQ(rec.expectedFrameCount, frameCount);
+
+    if (frameCount > 1u) {
+      // After parsing (the full file), all frames are complete.
+      for (size_t i = 0; i < frameCount; ++i)
+        EXPECT_TRUE(decoder->frameIsCompleteAtIndex(i));
+    } else {
+      // A single frame image is not reported complete until decoding.
+      EXPECT_FALSE(decoder->frameIsCompleteAtIndex(0));
+    }
+
+    frame = decoder->frameBufferAtIndex(0);
+    ASSERT_TRUE(frame);
+    EXPECT_EQ(ImageFrame::FrameComplete, frame->getStatus());
+    EXPECT_TRUE(decoder->frameIsCompleteAtIndex(0));
+  }
 }
 
 };  // namespace blink