Merge "Use null error_msg for pic images"

diff --cc runtime/gc/space/image_space.cc
index c0aa668,fe1c8e8..442a42e
--- 1/runtime/gc/space/image_space.cc
--- 2/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@@ -802,16 -807,14 +807,18 @@@ class ImageSpaceLoader 
            reinterpret_cast<char*>(map->Begin()) + decompress_offset,
            stored_size,
            map->Size() - decompress_offset);
 -      VLOG(image) << "Decompressing image took " << PrettyDuration(NanoTime() - start);
 +      const uint64_t time = NanoTime() - start;
 +      // Add one 1 ns to prevent possible divide by 0.
 +      VLOG(image) << "Decompressing image took " << PrettyDuration(time) << " ("
 +                  << PrettySize(static_cast<uint64_t>(map->Size()) * MsToNs(1000) / (time + 1))
 +                  << "/s)";
        if (decompressed_size + sizeof(ImageHeader) != image_header.GetImageSize()) {
-         *error_msg = StringPrintf(
-             "Decompressed size does not match expected image size %zu vs %zu",
-             decompressed_size + sizeof(ImageHeader),
-             image_header.GetImageSize());
+         if (error_msg != nullptr) {
+           *error_msg = StringPrintf(
+               "Decompressed size does not match expected image size %zu vs %zu",
+               decompressed_size + sizeof(ImageHeader),
+               image_header.GetImageSize());
+         }
          return nullptr;
        }
      }