Remove opaque alpha channel special case

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

Index: third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp b/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
index 905b2d3830a6bff94ca44cb1de4d2cbbbd979b13..1ec9790867af662420695eb08492b8b001f23137 100644
--- a/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
+++ b/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
@@ -346,7 +346,9 @@ TEST_F(DeferredImageDecoderTest, frameOpacity) {
     Vector<char> storage(size);
     SkPixmap pixmap(pix_info, storage.data(), row_bytes);
 
-    // Before decoding, the frame is not known to be opaque.
+    // Before decoding, the frame's alpha is unknown and assumed to be
+    // transparent. This works well with partial decoding, which will be
+    // transparent until the full first frame is decoded.
     sk_sp<SkImage> frame = decoder->CreateFrameAtIndex(0);
     ASSERT_TRUE(frame);
     EXPECT_FALSE(frame->isOpaque());
@@ -354,10 +356,13 @@ TEST_F(DeferredImageDecoderTest, frameOpacity) {
     // Force a lazy decode by reading pixels.
     EXPECT_TRUE(frame->readPixels(pixmap, 0, 0));
 
-    // After decoding, the frame is known to be opaque.
     frame = decoder->CreateFrameAtIndex(0);
     ASSERT_TRUE(frame);
-    EXPECT_TRUE(frame->isOpaque());
+    // When test_gif is true, we use a GIF file which is opaque.
+    // When test_gif is false we use a PNG file instead.
+    // Our PNG handling does not check if an image may be opaque, so it is
+    // treated as transparent.
+    EXPECT_EQ(test_gif, frame->isOpaque());
 
     // Re-generating the opaque-marked frame should not fail.
     EXPECT_TRUE(frame->readPixels(pixmap, 0, 0));