Fix std::memset usage in blob_memory_controller_unittest.cc.

This change exchanges the 2nd and 3rd parameters to std::memset() in a
number of places where the value to set and the length of the buffer
were inverted. The resulting incompletely initialized buffers triggered
MSan failures.

BUG=375297
TBR=dmurph@chromium.org

Review-Url: https://chromiumcodereview.appspot.com/2447473002
Cr-Commit-Position: refs/heads/master@{#426966}
1 file changed