Auto merge of #20132 - nakul02:issue_19223, r=jdm

Profiler for blocked IpcReceiver::recv()

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Implements feature #19223

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #19223 (github issue number if applicable).

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- [x] There are tests for these changes

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WIP.
@jdm - this is the new profiler : "Blocked at IPC Receive"
Should I dig through all the calls to `ipc::channel` and replace them with this profiled `IpcReceiver`?

![screenshot from 2018-02-27 01-35-37](https://user-images.githubusercontent.com/5394361/36721061-b46edea4-1b5e-11e8-91d6-7faba742f237.png)

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