Creating a new wrapper for gif decoder

BUG=skia:3257
BUG=skia:3534

Review URL: https://codereview.chromium.org/1022673011
diff --git a/src/codec/SkCodec.cpp b/src/codec/SkCodec.cpp
index 33cc9e1..4aa422c 100644
--- a/src/codec/SkCodec.cpp
+++ b/src/codec/SkCodec.cpp
@@ -8,9 +8,11 @@
 #include "SkCodec.h"
 #include "SkData.h"
 #include "SkCodec_libbmp.h"
+#include "SkCodec_libgif.h"
 #include "SkCodec_libico.h"
 #include "SkCodec_libpng.h"
 #include "SkCodec_wbmp.h"
+#include "SkCodecPriv.h"
 #include "SkStream.h"
 
 struct DecoderProc {
@@ -20,6 +22,7 @@
 
 static const DecoderProc gDecoderProcs[] = {
     { SkPngCodec::IsPng, SkPngCodec::NewFromStream },
+    { SkGifCodec::IsGif, SkGifCodec::NewFromStream },
     { SkIcoCodec::IsIco, SkIcoCodec::NewFromStream },
     { SkBmpCodec::IsBmp, SkBmpCodec::NewFromStream },
     { SkWbmpCodec::IsWbmp, SkWbmpCodec::NewFromStream }
@@ -29,6 +32,8 @@
     if (!stream) {
         return NULL;
     }
+    
+    SkCodec* codec = NULL;
     for (uint32_t i = 0; i < SK_ARRAY_COUNT(gDecoderProcs); i++) {
         DecoderProc proc = gDecoderProcs[i];
         const bool correctFormat = proc.IsFormat(stream);
@@ -36,10 +41,22 @@
             return NULL;
         }
         if (correctFormat) {
-            return proc.NewFromStream(stream);
+            codec = proc.NewFromStream(stream);
+            break;
         }
     }
-    return NULL;
+
+    // Set the max size at 128 megapixels (512 MB for kN32).
+    // This is about 4x smaller than a test image that takes a few minutes for
+    // dm to decode and draw.
+    const int32_t maxSize = 1 << 27;
+    if (codec != NULL &&
+            codec->getInfo().width() * codec->getInfo().height() > maxSize) {
+        SkCodecPrintf("Error: Image size too large, cannot decode.\n");
+        return NULL;
+    } else {
+        return codec;
+    }
 }
 
 SkCodec* SkCodec::NewFromData(SkData* data) {