Remove unnecessary decoded frame size overflow check

third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp

 /*
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 389 matching lines @@
   // If we used a LRU cache we would fill it and then on next animation loop
   // we would need to decode all the frames again -- the LRU would give no
   // benefit and would consume more memory.
   // So instead, simply purge unused frames if caching all of the frames of
   // the image would use more memory than the image decoder is allowed
   // (|max_decoded_bytes|) or would overflow 32 bits..
   //
   // As we decode we will learn the total number of frames, and thus total
   // possible image memory used.
 
-  const uint64_t frame_area = DecodedSize().Area();
-  const uint64_t frame_memory_usage = frame_area * 4;  // 4 bytes per pixel
-  if (frame_memory_usage / 4 != frame_area) {          // overflow occurred

[Srirama, 2017/05/30 07:07:39]

though it looks like it is doing nothing, this would have been added to detect
overflow. Please check the history of the CL why it was added to get a better
understanding. If it needs to be removed probably we need to remove the below
part of the code as well.
Anyway i will leave it to scroggo@ and noel@ to comment on this.

-    purge_aggressively_ = true;
-    return;
-  }
-
+  const uint64_t frame_memory_usage =
+      DecodedSize().Area() * 4;  // 4 bytes per pixel
   const uint64_t total_memory_usage = frame_memory_usage * index;
   if (total_memory_usage / frame_memory_usage != index) {  // overflow occurred
     purge_aggressively_ = true;
     return;
   }
 
   if (total_memory_usage > max_decoded_bytes_) {
     purge_aggressively_ = true;
   }
 }
@@ skipping 150 matching lines @@
     }
 
     // For color spaces without an identifiable gamut, just fall through to
     // sRGB.
   }
 
   return SkColorSpace::MakeSRGB();
 }
 
 }  // namespace blink