Remove opaque alpha channel special case

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

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
index cb37d138bd29caa3860fdbdb00875b763aa4a2d3..49a11b7dc51f1cccd0d476cf29d12b944fc5d163 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
@@ -51,8 +51,7 @@ PNGImageDecoder::PNGImageDecoder(AlphaOption alphaOption,
       // that as a signal to never check again, meaning the actual count will
       // never be respected.
       m_repetitionCount(cAnimationLoopOnce),
-      m_hasAlphaChannel(false),
-      m_currentBufferSawAlpha(false) {}
+      m_hasAlphaChannel(false) {}
 
 PNGImageDecoder::~PNGImageDecoder() {}
 
@@ -300,8 +299,6 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
         return;
       }
     }
-
-    m_currentBufferSawAlpha = false;
   }
 
   const IntRect& frameRect = buffer.originalFrameRect();
@@ -389,7 +386,6 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
       srcPtr = png_bytep(dstRow);
     }
 
-    unsigned alphaMask = 255;
     if (m_frameBufferCache[m_currentFrame].getAlphaBlendSource() ==
         ImageFrame::BlendAtopBgcolor) {
       if (buffer.premultiplyAlpha()) {
@@ -397,14 +393,12 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
              dstPixel++, srcPtr += 4) {
           buffer.setRGBAPremultiply(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
                                     srcPtr[3]);
-          alphaMask &= srcPtr[3];
         }
       } else {
         for (auto *dstPixel = dstRow; dstPixel < dstRow + width;
              dstPixel++, srcPtr += 4) {
           buffer.setRGBARaw(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
                             srcPtr[3]);
-          alphaMask &= srcPtr[3];
         }
       }
     } else {
@@ -417,21 +411,15 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
              dstPixel++, srcPtr += 4) {
           buffer.blendRGBAPremultiplied(dstPixel, srcPtr[0], srcPtr[1],
                                         srcPtr[2], srcPtr[3]);
-          alphaMask &= srcPtr[3];
         }
       } else {
         for (auto *dstPixel = dstRow; dstPixel < dstRow + width;
              dstPixel++, srcPtr += 4) {
           buffer.blendRGBARaw(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
                               srcPtr[3]);
-          alphaMask &= srcPtr[3];
         }
       }
     }
-
-    if (alphaMask != 255)
-      m_currentBufferSawAlpha = true;
-
   } else {
     for (auto *dstPixel = dstRow; dstPixel < dstRow + width;
          srcPtr += 3, ++dstPixel) {
@@ -463,9 +451,6 @@ void PNGImageDecoder::frameComplete() {
     return;
   }
 
-  if (!m_currentBufferSawAlpha)
-    correctAlphaWhenFrameBufferSawNoAlpha(m_currentFrame);
-
   buffer.setStatus(ImageFrame::FrameComplete);
 }