Because ProfilerMarkerPayload is the main type defined in these files, and
because the next patch is going to introduce ProfilerMarker.{h,cpp}, which
would be confusingly similar to the old names.
--HG--
rename : tools/profiler/core/ProfilerMarkers.cpp => tools/profiler/core/ProfilerMarkerPayload.cpp
rename : tools/profiler/public/ProfilerMarkers.h => tools/profiler/public/ProfilerMarkerPayload.h
extra : rebase_source : df22a2ab3867650348ae78fe959ff0366aff230b