IssueTracker

Please provide as much information as possible. At least, this should include a description of your issue and steps to reproduce the problem. If possible please provide a summary of what steps or workarounds you have already tried, and any docs or articles you found (un)helpful.

Problem you have encountered:
It is unclear what is being "measured" by the heap flamegraph.
In https://cloud.google.com/profiler/docs/concepts-profiling#heap_memory_consumption it says that for Go programs, both heap usage and heap allocations are supported, but both in the stackdriver profiler interface and in its documentation (https://cloud.google.com/profiler/docs/using-profiler#profile-config) there is only one "Heap" option.

What you expected to happen:
In the stackdriver profiler be able to:
- select which type of heap profile type to display; whether usage or allocations
- when I select heap usage, the metrics shown (in the tooltips displayed when hovering) should make it clear that this is an instantaneous measurement
- when I select heap allocations, the metrics shown should make it clear that this is a rate of allocation (e.g. bytes/s or obj/s).
- when I read the documentation, I am able to quickly figure out what kind of profiling type I need to troubleshoot specific issues, and I get clear, consistent and actionable steps to use the profiler to that end

Steps to reproduce:
Open the heap profile, notice that only one option is available
Open the heap profiler documentation, notice that they are unclear and inconsistent

Other information (workarounds you have tried, documentation consulted, etc):