Index8 GPU and CPU raster support.

src/core/SkImageGenerator.cpp

Index: src/core/SkImageGenerator.cpp
diff --git a/src/core/SkImageGenerator.cpp b/src/core/SkImageGenerator.cpp
index 5e401920cd97a68cf5cb5e88e73a3fa9d6092c99..3712c4c46b99c1ca880afe8b5554f5ff365f16d6 100644
--- a/src/core/SkImageGenerator.cpp
+++ b/src/core/SkImageGenerator.cpp
@@ -177,6 +177,14 @@ bool SkImageGenerator::tryGenerateBitmap(SkBitmap* bitmap, const SkImageInfo* in
     int ctCount = 0;
     if (!this->getPixels(bitmap->info(), bitmap->getPixels(), bitmap->rowBytes(),
                          ctStorage, &ctCount)) {
+        // Generator failing to decode to declared colorType, could decode to N32.
+        // This is important for Chromium Index8 decoding - GIF multiframe animation frames are
+        // decoded to Index8 format by default but in rare cases some of the frames are N32.
+        if (bitmap->colorType() != kN32_SkColorType) {
+            bitmap->reset();
+            info = SkImageInfo::MakeN32(info.width(), info.height(), info.alphaType());
+            return tryGenerateBitmap(bitmap, &info, allocator);
+        }
         return reset_and_return_false(bitmap);
     }