Don't read random data in ICO check.

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 4d19714a11b20c134aa9e6e38c3849529b50f798..513a1b59c06a9a870d9b785df668cbf140b21e01 100644
--- a/src/images/SkImageDecoder_libico.cpp
+++ b/src/images/SkImageDecoder_libico.cpp
@@ -407,7 +407,9 @@ static bool is_ico(SkStreamRewindable* stream) {
     // FIXME: Is that required and sufficient?
     SkAutoMalloc autoMal(4);
     unsigned char* buf = (unsigned char*)autoMal.get();
-    stream->read((void*)buf, 4);
+    if (stream->read((void*)buf, 4) < 4) {
+        return false;
+    }
     int reserved = read2Bytes(buf, 0);
     int type = read2Bytes(buf, 2);
     if (reserved != 0 || type != 1) {