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 2e0e007cc221b427abeb514d1eeb28400a623a86..a56b153a260028d0e60383479c2935a12178fe2f 100644
--- a/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
+++ b/third_party/WebKit/Source/platform/graphics/DeferredImageDecoderTest.cpp
@@ -342,7 +342,9 @@ 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());
@@ -353,7 +355,9 @@ TEST_F(DeferredImageDecoderTest, frameOpacity) {
     // After decoding, the frame is known to be opaque.

[scroggo_chromium, 2017/05/08 14:56:36]

This line looks to be no longer true.

[cblume, 2017/05/25 06:52:36]

Done.

     frame = decoder->CreateFrameAtIndex(0);
     ASSERT_TRUE(frame);
-    EXPECT_TRUE(frame->isOpaque());
+    // The GIF file specifies it is opaque.
+    // Without the file, we remain at the default: transparent

[scroggo_chromium, 2017/05/08 14:56:36]

When test_gif is false, it means that data_ is a PNG, so this really means that
we're testing PNG, not testing without a file. (Maybe this for loop should be
made more clear?)

[cblume, 2017/05/25 06:52:36]

Done.

+    EXPECT_EQ(test_gif, frame->isOpaque());
 
     // Re-generating the opaque-marked frame should not fail.
     EXPECT_TRUE(frame->readPixels(pixmap, 0, 0));