Added documentation for running perf bisects and tryjobs.

docs/speed/perf_trybots.md

+# Perf Try Bots
+
+[TOC]
+
+## What are perf try bots?
+
+Chrome has a performance lab with dozens of device and OS configurations. You
+can run performance tests on an unsubmitted CL on these devices using the
+perf try bots.
+
+## Supported platforms
+
+The platforms available in the lab change over time. To find the currently
+available platforms, run `tools/perf/run_benchmark try --help`.
+
+Example output:
+
+```
+> tools/perf/run_benchmark try --help
+usage: Run telemetry benchmarks on trybot. You can add all the benchmark options available except the --browser option
+       [-h] [--repo_path <repo path>] [--deps_revision <deps revision>]
+       <trybot name> <benchmark name>
+
+positional arguments:
+  <trybot name>         specify which bots to run telemetry benchmarks on.  Allowed values are:
+                        Mac Builder
+                        all
+                        all-android
+                        all-linux
+                        all-mac
+                        all-win
+                        android-fyi
+                        android-nexus5
+                        android-nexus5X
+                        android-nexus6
+                        android-nexus7
+                        android-one
+                        android-webview-arm64-aosp
+                        android-webview-nexus6-aosp
+                        linux
+                        mac-10-11
+                        mac-10-12
+                        mac-10-12-mini-8gb
+                        mac-air
+                        mac-pro
+                        mac-retina
+                        staging-android-nexus5X
+                        staging-linux
+                        staging-mac-10-12
+                        staging-win
+                        win
+                        win-8
+                        win-x64
+                        winx64-10
+                        winx64-high-dpi
+                        winx64-zen
+                        winx64ati
+                        winx64intel
+                        winx64nvidia
+
+```
+
+## Supported benchmarks
+
+All the telemetry benchmarks are supported by the perf trybots. To get a full
+list, run `tools/perf/run_benchmark list`.
+
+To learn more about the benchmark, you can read about the
+[system health benchmarks](https://docs.google.com/document/d/1BM_6lBrPzpMNMtcyi2NFKGIzmzIQ1oH3OlNG27kDGNU/edit?ts=57e92782),
+which test Chrome's performance at a high level, and the
+[benchmark harnesses](https://docs.google.com/spreadsheets/d/1ZdQ9OHqEjF5v8dqNjd7lGUjJnK6sgi8MiqO7eZVMgD0/edit#gid=0),
+which cover more specific areas.
+
+## Starting a perf try job
+
+Use this command line:
+
+`tools/perf/run_benchmark try <trybot_name> <benchmark_name>`
+
+See above for how to choose a trybot and benchmark.
+
+Run `tools/perf/run_benchmark try --help` for more information about available
+options.
+
+## Interpreting the results
+
+Perf trybots create a code review under the covers to hold the trybot results.
+The code review will list links to buildbot status pages for the try jobs.
+On each buildbot status page, you will see a "HTML Results" link. You can click
+it to see detailed information about the performance test results with and
+without your patch.
+
+**[Here is the documentation](https://github.com/catapult-project/catapult/blob/master/docs/metrics-results-ui.md)**
+on reading the results.