Windows components: picked automatically by each game's source (#554)

Each game's Windows components now come from the list its own source
trusts, and the ones that list names turn on by themselves. The user's own
on/off switches always win; each automatic row says why it is on.

- Steam games: the Steamworks Shared redistributables Steam installs with
  the game (appmanifest SharedDepots, else the client's appinfo.vdf).
  Steam keeps its install scripts marked as already run.
- GOG: the build manifest's dependencies. Epic: the manifest's
  prerequisite (Unreal's maps to VC++ and DirectX). Amazon: fuel.json
  PostInstall. Older GOG/Epic installs get their list fetched once with the
  saved sign-in; game files are never downloaded again.
- Custom games (the + button, Add all, migrated folders): one shared Steam
  match per game, also used for artwork. An appid from the game's files
  turns components on; a name-only match stays Recommended; no match falls
  back to the folder scan.
- Steam app info for apps the client never saw comes from an anonymous
  Steam PICS lookup (CM websocket, anonymous logon, product info), cached
  per appid; the user's Steam sign-in is never used.
- Missing components download in the background on one low-priority
  worker that pauses during sessions and waits on battery saver, heat or a
  metered network unless the user asked. A game Steam installs during a
  session is readied right away so it can be played without ending the
  session; the launch waits up to 10 s only for a component still on its
  way.
- Page: "On for this game" with reasons, a quiet "Checking what this game
  needs..." only for games never worked out, rows that ease in, pieces that
  need a download greyed out while offline. The intro names no other app.
- The folder scan skips Unity's *_Data/Managed (Mono, not .NET Framework).

tools/tests/test_wincomponents.py

@@ -137,7 +137,7 @@ class WinComponentsTest(unittest.TestCase):
         self.pick("openal")
         globals_ = GAME_ENV["win_components"].__globals__
         real = runpy.run_path(str(BIN / "droiddeck-wincomponents"))
-        real["apply"].__defaults__ = (self.selection, self.store)
+        real["apply"].__defaults__ = (self.selection, self.store, self.selection.parent / "no-pending.json", None)
         with mock.patch.dict(globals_, {"runpy": mock.Mock(run_path=lambda _path: real)}):
             self.assertEqual(GAME_ENV["win_components"](str(self.compat) + "/", "2571976725"), "openal32=n,b")
             self.assertEqual(GAME_ENV["win_components"]("", "2571976725"), "")
@@ -166,5 +166,58 @@ class WinComponentsTest(unittest.TestCase):
         self.assertEqual(MODULE["overrides_value"](["a", "b=n", "a=b", "bad;name", "c=x"]), "b=n;a=b")
 
 
+class PendingWaitTest(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        root = Path(self.tmp.name)
+        self.store = root / "store"
+        self.pending = root / "pending.json"
+        self.slept = []
+
+    def tearDown(self):
+        self.tmp.cleanup()
+
+    def install(self, cid):
+        folder = self.store / cid
+        folder.mkdir(parents=True, exist_ok=True)
+        (folder / "component.json").write_text(json.dumps({"id": cid, "overrides": []}))
+
+    def clock(self):
+        return len(self.slept) * 0.5
+
+    def wait(self, timeout=10.0, on_sleep=None):
+        def sleep(seconds):
+            self.slept.append(seconds)
+            if on_sleep:
+                on_sleep(len(self.slept))
+        return MODULE["wait_for_pending"]("1262580", self.pending, self.store, timeout, sleep, self.clock)
+
+    def test_nothing_pending_means_no_wait(self):
+        self.assertIsNone(self.wait())
+        self.pending.write_text(json.dumps({"games": {"999": ["d3dx9"]}}))
+        self.assertIsNone(self.wait())
+        self.install("d3dx9")
+        self.pending.write_text(json.dumps({"games": {"1262580": ["d3dx9"]}}))
+        self.assertIsNone(self.wait())
+        self.assertEqual([], self.slept)
+
+    def test_waits_until_the_component_lands(self):
+        self.pending.write_text(json.dumps({"games": {"1262580": ["vcredist2019_dll"]}}))
+        note = self.wait(on_sleep=lambda n: self.install("vcredist2019_dll") if n == 3 else None)
+        self.assertEqual(3, len(self.slept))
+        self.assertEqual("wincomp: 1262580 waited 1500ms for vcredist2019_dll", note)
+
+    def test_gives_up_cleanly_after_the_timeout(self):
+        self.pending.write_text(json.dumps({"games": {"1262580": ["vcredist2019_dll", "d3dx9"]}}))
+        self.install("d3dx9")
+        note = self.wait(timeout=2.0)
+        self.assertEqual(4, len(self.slept))
+        self.assertEqual("wincomp: 1262580 launched without vcredist2019_dll (not ready)", note)
+
+    def test_a_damaged_pending_file_is_no_wait(self):
+        self.pending.write_text("{not json")
+        self.assertIsNone(self.wait())
+
+
 if __name__ == "__main__":
     unittest.main()