Expose more info in SkCodec::FrameInfo

Bug: b/160984428

Add more fields to SkCodec::FrameInfo, which describes the properties of
an individual frame in an animated image. This allows a client that
wishes to seek to determine frame dependencies so that they can decode
an arbitrary frame, which in turn will allow SkCodec to remove
SkCodec::FrameInfo::fRequiredFrame. Currently, SkCodec seeks through the
stream to determine frame dependencies, but this is unnecessary work
(and storage) for a client that does not want to seek.

These fields also support the proposed APIs in go/animated-ndk.

Move SkCodecAnimation::Blend from SkCodecAnimationPriv (and delete that
file) into SkCodecAnimation.h. Rename its values to be more clear.

Merge common code for populating SkCodec::FrameInfo.

Add a test for a GIF with offsets outside the range of the image. Note
that libwebp rejects such an image.

Update libgifcodec.

Change-Id: Ie27e0531e7d62eaae153eccb3105bf2121b5aac4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/339857
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Nigel Tao <nigeltao@google.com>
diff --git a/src/codec/SkWebpCodec.cpp b/src/codec/SkWebpCodec.cpp
index b66d576..e8b1bb4 100644
--- a/src/codec/SkWebpCodec.cpp
+++ b/src/codec/SkWebpCodec.cpp
@@ -12,7 +12,6 @@
 #include "include/core/SkCanvas.h"
 #include "include/private/SkTemplates.h"
 #include "include/private/SkTo.h"
-#include "src/codec/SkCodecAnimationPriv.h"
 #include "src/codec/SkCodecPriv.h"
 #include "src/codec/SkParseEncodedOrigin.h"
 #include "src/codec/SkSampler.h"
@@ -266,7 +265,7 @@
                 SkCodecAnimation::DisposalMethod::kKeep);
         frame->setDuration(iter.duration);
         if (WEBP_MUX_BLEND != iter.blend_method) {
-            frame->setBlend(SkCodecAnimation::Blend::kBG);
+            frame->setBlend(SkCodecAnimation::Blend::kSrc);
         }
         fFrameHolder.setAlphaAndRequiredFrame(frame);
     }
@@ -295,14 +294,9 @@
     }
 
     if (frameInfo) {
-        frameInfo->fRequiredFrame = frame->getRequiredFrame();
-        frameInfo->fDuration = frame->getDuration();
         // libwebp only reports fully received frames for an
         // animated image.
-        frameInfo->fFullyReceived = true;
-        frameInfo->fAlphaType = frame->hasAlpha() ? kUnpremul_SkAlphaType
-                                                  : kOpaque_SkAlphaType;
-        frameInfo->fDisposalMethod = frame->getDisposalMethod();
+        frame->fillIn(frameInfo, true);
     }
 
     return true;