Allow ico decoder to decode PNG sub-images.

src/images/SkImageDecoder_libico.cpp

Index: src/images/SkImageDecoder_libico.cpp
diff --git a/src/images/SkImageDecoder_libico.cpp b/src/images/SkImageDecoder_libico.cpp
index 195b6ff08b9338ee4c4502b4efb6f5b5a2c31785..04978b00c19333b8b37ed3c3eda0248086f68605 100644
--- a/src/images/SkImageDecoder_libico.cpp
+++ b/src/images/SkImageDecoder_libico.cpp
@@ -152,6 +152,20 @@ bool SkICOImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode)
     int offset = read4Bytes(buf, 18 + choice*16);
     if ((size_t)(offset + size) > length)
         return false;
+
+    // Check to see if this is a PNG image inside the ICO
+    {
+        SkMemoryStream subStream(buf + offset, size, false);
+        SkAutoTDelete<SkImageDecoder> otherDecoder(SkImageDecoder::Factory(&subStream));
+        if (otherDecoder.get() != NULL) {
+            // Set fields on the other decoder to be the same as this one.
+            this->copyFieldsToOther(otherDecoder.get());
+            if(otherDecoder->decode(&subStream, bm, this->getDefaultPref(), mode)) {
+                return true;
+            }
+        }
+    }
+
     //int infoSize = read4Bytes(buf, offset);             //40
     //int width = read4Bytes(buf, offset+4);              //should == w
     //int height = read4Bytes(buf, offset+8);             //should == 2*h