Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp

Index: third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
index 29eefb7ce6fda231c01f26935684a23ac5c31bbf..923cc10e10c22dc32c4cbc64855db08df8d37ece 100644
--- a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
+++ b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
@@ -100,6 +100,26 @@ bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info,
   return decoded;
 }
 
+bool DecodingImageGenerator::onGenerateScaledPixels(
+    const SkISize& scaledSize,
+    const SkIPoint& subsetOrigin,
+    const SkPixmap& subsetPixels,
+    SkFilterQuality quality) {
+  TRACE_EVENT1("blink", "DecodingImageGenerator::onGenerateScaledPixels",
+               "frame index", static_cast<int>(m_frameIndex));
+  // TODO(aleksandar.stojiljkovic): sub-rect decoding, see crbug.com/671821.
+  if (!subsetOrigin.isZero() || subsetPixels.width() != scaledSize.width() ||
+      subsetPixels.height() != subsetPixels.height())
+    return false;
+  PlatformInstrumentation::willDecodeLazyPixelRef(uniqueID());
+  bool decoded = m_frameGenerator->decodeAndScale(
+      m_data.get(), m_allDataReceived, m_frameIndex,
+      getInfo().makeWH(scaledSize.width(), scaledSize.height()),
+      subsetPixels.writable_addr(), subsetPixels.rowBytes(), quality);
+  PlatformInstrumentation::didDecodeLazyPixelRef();
+  return decoded;
+}
+
 bool DecodingImageGenerator::onQueryYUV8(SkYUVSizeInfo* sizeInfo,
                                          SkYUVColorSpace* colorSpace) const {
   // YUV decoding does not currently support progressive decoding. See comment