Prevent webp from producing 0 dimensional images

src/codec/SkWebpCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkWebpCodec.h"
 #include "SkImageGenerator.h"
 #include "SkTemplates.h"
@@ skipping 85 matching lines @@
     }
     if (dst.alphaType() == src.alphaType()) {
         return true;
     }
     return kPremul_SkAlphaType == dst.alphaType() &&
             kUnpremul_SkAlphaType == src.alphaType();
 }
 
 SkISize SkWebpCodec::onGetScaledDimensions(float desiredScale) const {
     SkISize dim = this->getInfo().dimensions();
-    dim.fWidth = SkScalarRoundToInt(desiredScale * dim.fWidth);
-    dim.fHeight = SkScalarRoundToInt(desiredScale * dim.fHeight);
+    // SkCodec treats zero dimensional images as errors, so the minimum size
+    // that we will recommend is 1x1.
+    dim.fWidth = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fWidth));
+    dim.fHeight = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fHeight));
     return dim;
 }
 
 static WEBP_CSP_MODE webp_decode_mode(SkColorType ct, bool premultiply) {
     switch (ct) {
         case kBGRA_8888_SkColorType:
             return premultiply ? MODE_bgrA : MODE_BGRA;
         case kRGBA_8888_SkColorType:
             return premultiply ? MODE_rgbA : MODE_RGBA;
         default:
@@ skipping 73 matching lines @@
                 // Break out of the switch statement. Continue the loop.
                 break;
             default:
                 return kInvalidInput;
         }
     }
 }
 
 SkWebpCodec::SkWebpCodec(const SkImageInfo& info, SkStream* stream)
     : INHERITED(info, stream) {}