Ship a baseline profile, generated on the emulator because the phone cannot collect one

The profile is real: 13193 lines in app/src/main/baseline-prof.txt, 584 of them the app's own classes, bundled into the release APK as assets/dexopt/baseline.prof. It is produced by a new :baselineprofile test module that walks the first journey - roots screen, one volume opened - under the androidx.baselineprofile plugin, and :app now depends on androidx.profileinstaller so the bundled profile is applied at install time.

Two device facts decided how it was made. Collection requires API 33+ (BaselineProfileRule refuses Android 12 outright), so it ran on the API 35 AVD that was already in ~/.android/avd; that emulator is software-rendered and needs androidx.benchmark.suppressErrors=EMULATOR for any macrobenchmark. And the release build needed profileable android:shell=true, which is why app/src/release/AndroidManifest.xml exists and says why: the same APK is both the thing measured and the thing shipped, so the profile's class names are the ones in the shipped dex.

The effect is not measured, and PERFORMANCE.md says so: 7404 ms median without the profile against 9005 ms with it, run to run, because a TCG emulator varies by more than a profile can buy. What remains is one run on a physical API 33+ phone, with the two compile commands documented. The emulator did settle the other open question - FrameTimingMetric there reports frameDurationCpuMs and frameOverrunMs, the metrics this phone cannot produce at all.

:baselineprofile is compiled by tools/verify.sh --release like :benchmark, so it cannot rot between device runs.

app/src/release/AndroidManifest.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  `<profileable android:shell="true"/>` on the release build.
+
+  The baseline-profile generator (`:baselineprofile`) has to profile the app it is generating for, and
+  profiling requires this flag — see the same element in `src/benchmark/AndroidManifest.xml`, where it is
+  required for the macrobenchmarks. `shell="true"` means only the adb shell may profile the process: no
+  other app can, and nothing about the profile is exposed to a user. Shipping it is what lets the profile
+  be regenerated against the *release* build rather than a lookalike, so the class names in
+  `src/main/baseline-prof.txt` are exactly the ones in the shipped dex.
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <application>
+        <profileable android:shell="true" />
+    </application>
+</manifest>