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

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

Index: third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp b/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
index d6c4fc34590f90d78f41595338b3aaec26524d9f..b39997b8cc49ae97fccc1075d531410741940603 100644
--- a/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
+++ b/third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.cpp
@@ -122,24 +122,25 @@ bool ImageFrameGenerator::decodeAndScale(SegmentReader* data,
                                          size_t index,
                                          const SkImageInfo& info,
                                          void* pixels,
-                                         size_t rowBytes) {
+                                         size_t rowBytes,
+                                         SkFilterQuality quality) {
   if (m_decodeFailed)
     return false;
 
   TRACE_EVENT1("blink", "ImageFrameGenerator::decodeAndScale", "frame index",
                static_cast<int>(index));
 
-  // This implementation does not support scaling so check the requested size.
   SkISize scaledSize = SkISize::Make(info.width(), info.height());
-  ASSERT(m_fullSize == scaledSize);
+  const bool doScaleAfterDecoding = m_fullSize != scaledSize;
 
   // It is okay to allocate ref-counted ExternalMemoryAllocator on the stack,
   // because 1) it contains references to memory that will be invalid after
   // returning (i.e. a pointer to |pixels|) and therefore 2) should not live
   // longer than the call to the current method.
   ExternalMemoryAllocator externalAllocator(info, pixels, rowBytes);
-  SkBitmap bitmap = tryToResumeDecode(data, allDataReceived, index, scaledSize,
-                                      &externalAllocator);
+  SkBitmap bitmap =
+      tryToResumeDecode(data, allDataReceived, index, m_fullSize,
+                        doScaleAfterDecoding ? nullptr : &externalAllocator);
   DCHECK(externalAllocator.unique());  // Verify we have the only ref-count.
 
   if (bitmap.isNull())
@@ -147,11 +148,17 @@ bool ImageFrameGenerator::decodeAndScale(SegmentReader* data,
 
   // Check to see if the decoder has written directly to the pixel memory
   // provided. If not, make a copy.
-  ASSERT(bitmap.width() == scaledSize.width());
-  ASSERT(bitmap.height() == scaledSize.height());
+  DCHECK_NE(bitmap.width(), m_fullSize.width());
+  DCHECK_NE(bitmap.height(), m_fullSize.height());
   SkAutoLockPixels bitmapLock(bitmap);
-  if (bitmap.getPixels() != pixels)
-    return bitmap.copyPixelsTo(pixels, rowBytes * info.height(), rowBytes);
+  if (bitmap.getPixels() != pixels) {
+    if (!doScaleAfterDecoding)
+      return bitmap.copyPixelsTo(pixels, rowBytes * info.height(), rowBytes);
+    SkPixmap pixmap;
+    SkPixmap scaled(info, pixels, rowBytes);
+    return bitmap.peekPixels(&pixmap) && pixmap.scalePixels(scaled, quality);
+  }
+  DCHECK(!doScaleAfterDecoding);
   return true;
 }