Fix ICO bug exposed by the fuzzer

src/codec/SkBmpStandardCodec.cpp

Index: src/codec/SkBmpStandardCodec.cpp
diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index 358da057c6e8a22ceea8dd9370e6b5da4982f961..258a6f779c73cc8c9acc05bca39c13605b128a95 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -150,13 +150,23 @@ SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
 }
 
 void SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
-    // In the case of paletted ico-in-bmps, we will report BGRA to the client,
-    // since we may be required to apply an alpha mask after the decode.  But
-    // the swizzler needs to know the actual format of the bmp.
+    // In the case of ico-in-bmps, we will report BGRA to the client,

[scroggo, 2016/05/04 13:02:19]

nit: Shouldn't this be bmp-in-icos?

[msarett, 2016/05/04 19:27:49]

Done.

+    // since we may be required to apply an alpha mask after the decode.
+    // However, the swizzler needs to know the actual format of the bmp.
     SkEncodedInfo swizzlerInfo = this->getEncodedInfo();
-    if (fInIco && this->bitsPerPixel() <= 8) {
-        swizzlerInfo = SkEncodedInfo::Make(SkEncodedInfo::kPalette_Color, swizzlerInfo.alpha(),
-                this->bitsPerPixel());
+    if (fInIco) {
+        switch (this->bitsPerPixel()) {
+            case 8:

[scroggo, 2016/05/04 13:02:19]

We used to handle <= 8. I take it < was unnecessary?

[msarett, 2016/05/04 19:27:49]

Nice catch!  This is me trying to introduce a new bug.  <= 8 is correct, I'll
fix this.

+                swizzlerInfo = SkEncodedInfo::Make(SkEncodedInfo::kPalette_Color,
+                        swizzlerInfo.alpha(), this->bitsPerPixel());

[scroggo, 2016/05/04 13:02:19]

8?

[msarett, 2016/05/04 19:27:49]

It could be 1, 2, 4, or 8.

+                break;
+            case 24:
+                swizzlerInfo = SkEncodedInfo::Make(SkEncodedInfo::kBGR_Color,
+                        SkEncodedInfo::kOpaque_Alpha, swizzlerInfo.bitsPerComponent());

[scroggo, 2016/05/04 13:02:19]

Why do you need to check bitsPerComponent here? Will it ever be anything other
than 8? If so, it seems like something doesn't match up.

[msarett, 2016/05/04 19:27:49]

It will always be 8.  I'll put 8.

+                break;
+            default:
+                break;
+        }
     }
 
     // Get a pointer to the color table if it exists