Added a dumpstate readme for development.

# `dumpstate` development tips

## To build `dumpstate`

Do a full build first:

```

m -j dumpstate

```

Then incremental ones:

```

mmm -j frameworks/native/cmds/dumpstate

```

If you're working on device-specific code, you might need to build them as well. Example:

```

mmm -j frameworks/native/cmds/dumpstate device/acme/secret_device/dumpstate/ hardware/interfaces/dumpstate

```

## To build, deploy, and take a bugreport

```

mmm -j frameworks/native/cmds/dumpstate && adb push ${OUT}/system/bin/dumpstate system/bin && adb shell am bug-report

```

## To build, deploy, and run unit tests

First create `/data/nativetest`:

```

adb shell mkdir /data/nativetest

```

Then run:

```

mmm -j frameworks/native/cmds/dumpstate/ && adb push ${OUT}/data/nativetest/dumpstate_test* /data/nativetest && adb shell /data/nativetest/dumpstate_test/dumpstate_test

```

And to run just one test (for example, `DumpstateTest.RunCommandNoArgs`):

```

mmm -j frameworks/native/cmds/dumpstate/ && adb push ${OUT}/data/nativetest/dumpstate_test* /data/nativetest && adb shell /data/nativetest/dumpstate_test/dumpstate_test --gtest_filter=DumpstateTest.RunCommandNoArgs

```

## To take quick bugreports

```

adb shell setprop dumpstate.dry_run true

```

## To change the `dumpstate` version

```

adb shell setprop dumpstate.version VERSION_NAME

```

Example:

```

adb shell setprop dumpstate.version split-dumpsys && adb shell dumpstate -v

```

Then to restore the default version:

```

adb shell setprop dumpstate.version default

```

## Code style and formatting

Use the style defined at the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html)

and make sure to run the following command prior to `repo upload`:

```

git clang-format --style=file HEAD~

```

## Useful Bash tricks

```

export BR_DIR=/bugreports

alias br='adb shell cmd activity bug-report'

alias ls_bugs='adb shell ls -l ${BR_DIR}/'

unzip_bug() {

  adb pull ${BR_DIR}/$1 && emacs $1 && mv $1 /tmp

}

less_bug() {

  adb pull ${BR_DIR}/$1 && less $1 && mv $1 /tmp

}

rm_bugs() {

 if [ -z "${BR_DIR}" ] ; then echo "Variable BR_DIR not set"; else adb shell rm -rf ${BR_DIR}/*; fi

}

```