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 0e12da8491b7094abc87fe1dd4647a97b07fd634..c2387ea4acfa1a61dec5f3d1d3db88a815bc2d3c 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 alpha_option,
       // that as a signal to never check again, meaning the actual count will
       // never be respected.
       repetition_count_(kAnimationLoopOnce),
-      has_alpha_channel_(false),
-      current_buffer_saw_alpha_(false) {}
+      has_alpha_channel_(false) {}
 
 PNGImageDecoder::~PNGImageDecoder() {}
 
@@ -298,8 +297,6 @@ void PNGImageDecoder::RowAvailable(unsigned char* row_buffer,
         return;
       }
     }
-
-    current_buffer_saw_alpha_ = false;
   }
 
   const IntRect& frame_rect = buffer.OriginalFrameRect();
@@ -387,7 +384,6 @@ void PNGImageDecoder::RowAvailable(unsigned char* row_buffer,
       src_ptr = png_bytep(dst_row);
     }
 
-    unsigned alpha_mask = 255;
     if (frame_buffer_cache_[current_frame_].GetAlphaBlendSource() ==
         ImageFrame::kBlendAtopBgcolor) {
       if (buffer.PremultiplyAlpha()) {
@@ -395,14 +391,12 @@ void PNGImageDecoder::RowAvailable(unsigned char* row_buffer,
              dst_pixel++, src_ptr += 4) {
           ImageFrame::SetRGBAPremultiply(dst_pixel, src_ptr[0], src_ptr[1],
                                          src_ptr[2], src_ptr[3]);
-          alpha_mask &= src_ptr[3];
         }
       } else {
         for (auto *dst_pixel = dst_row; dst_pixel < dst_row + width;
              dst_pixel++, src_ptr += 4) {
           ImageFrame::SetRGBARaw(dst_pixel, src_ptr[0], src_ptr[1], src_ptr[2],
                                  src_ptr[3]);
-          alpha_mask &= src_ptr[3];
         }
       }
     } else {
@@ -415,21 +409,15 @@ void PNGImageDecoder::RowAvailable(unsigned char* row_buffer,
              dst_pixel++, src_ptr += 4) {
           ImageFrame::BlendRGBAPremultiplied(dst_pixel, src_ptr[0], src_ptr[1],
                                              src_ptr[2], src_ptr[3]);
-          alpha_mask &= src_ptr[3];
         }
       } else {
         for (auto *dst_pixel = dst_row; dst_pixel < dst_row + width;
              dst_pixel++, src_ptr += 4) {
           ImageFrame::BlendRGBARaw(dst_pixel, src_ptr[0], src_ptr[1],
                                    src_ptr[2], src_ptr[3]);
-          alpha_mask &= src_ptr[3];
         }
       }
     }
-
-    if (alpha_mask != 255)
-      current_buffer_saw_alpha_ = true;
-
   } else {
     for (auto *dst_pixel = dst_row; dst_pixel < dst_row + width;
          src_ptr += 3, ++dst_pixel) {
@@ -462,9 +450,6 @@ void PNGImageDecoder::FrameComplete() {
     return;
   }
 
-  if (!current_buffer_saw_alpha_)
-    CorrectAlphaWhenFrameBufferSawNoAlpha(current_frame_);
-
   buffer.SetStatus(ImageFrame::kFrameComplete);
 }