Revert "Revert "Disallow readPixels() conversions from untagged srcs to tagged dsts""

This reverts commit 8461506c8b025522eb89cd754c63fb5dbf0cb7f1.

Reason for revert: Fixed some Chrome code, let's try this again.

Original change's description:
> Revert "Disallow readPixels() conversions from untagged srcs to tagged dsts"
> 
> This reverts commit ccfd1083a7b9d546735ddd1037f3240635cce72d.
> 
> Reason for revert: Roll is failing.
> 
> Original change's description:
> > Disallow readPixels() conversions from untagged srcs to tagged dsts
> > 
> > This might break the roll into Chrome.  But let's see how.
> > 
> > BUG=skia:6021
> > 
> > Change-Id: I2698b5d6fe72d01bed0dc64703b592a03d441a80
> > Reviewed-on: https://skia-review.googlesource.com/7127
> > Reviewed-by: Mike Reed <reed@google.com>
> > Commit-Queue: Matt Sarett <msarett@google.com>
> > 
> 
> TBR=msarett@google.com,brianosman@google.com,reed@google.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:6021
> 
> Change-Id: I4b62178fd7c23f43cf69ca69fc14526ecd503956
> Reviewed-on: https://skia-review.googlesource.com/7205
> Commit-Queue: Matt Sarett <msarett@google.com>
> Reviewed-by: Matt Sarett <msarett@google.com>
> 

TBR=msarett@google.com,brianosman@google.com,reed@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
BUG=skia:6021

Change-Id: I3f3f33fe6b84fbd5c537b60ed5c8b9201d529a6a
Reviewed-on: https://skia-review.googlesource.com/8156
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
diff --git a/tests/ImageTest.cpp b/tests/ImageTest.cpp
index c4f8abb..4f5f56f 100644
--- a/tests/ImageTest.cpp
+++ b/tests/ImageTest.cpp
@@ -34,6 +34,14 @@
 
 using namespace sk_gpu_test;
 
+SkImageInfo read_pixels_info(SkImage* image) {
+    if (as_IB(image)->onImageInfo().colorSpace()) {
+        return SkImageInfo::MakeS32(image->width(), image->height(), image->alphaType());
+    }
+
+    return SkImageInfo::MakeN32(image->width(), image->height(), image->alphaType());
+}
+
 static void assert_equal(skiatest::Reporter* reporter, SkImage* a, const SkIRect* subsetA,
                          SkImage* b) {
     const int widthA = subsetA ? subsetA->width() : a->width();
@@ -45,11 +53,9 @@
     // see https://bug.skia.org/3965
     //REPORTER_ASSERT(reporter, a->isOpaque() == b->isOpaque());
 
-    // The codecs may have given us back F16, we can't read from F16 raster to N32, only S32.
-    SkImageInfo info = SkImageInfo::MakeS32(widthA, heightA, a->alphaType());
     SkAutoPixmapStorage pmapA, pmapB;
-    pmapA.alloc(info);
-    pmapB.alloc(info);
+    pmapA.alloc(read_pixels_info(a));
+    pmapB.alloc(read_pixels_info(b));
 
     const int srcX = subsetA ? subsetA->x() : 0;
     const int srcY = subsetA ? subsetA->y() : 0;
@@ -57,7 +63,7 @@
     REPORTER_ASSERT(reporter, a->readPixels(pmapA, srcX, srcY));
     REPORTER_ASSERT(reporter, b->readPixels(pmapB, 0, 0));
 
-    const size_t widthBytes = widthA * info.bytesPerPixel();
+    const size_t widthBytes = widthA * 4;
     for (int y = 0; y < heightA; ++y) {
         REPORTER_ASSERT(reporter, !memcmp(pmapA.addr32(0, y), pmapB.addr32(0, y), widthBytes));
     }