Dark boot on dark theme.

Bug: 113028175
Bug: 134430124
Test: Build and flash taimen with the matching bootloader change. Toggle
      dark mode in Settings. Check serial log regarding the start of
      vendor.theme_{set,clear} services. Also read the value via `dd bs=1
      skip=2048 if=/dev/block/sda5 count=32 | xxd` to confirm the change.
Test: Trigger a factory reset via Settings. Check the value in /misc
      after the reset.
Change-Id: I3ae9ac41d689a4d0a9d5e0275de92c35dda068b7

BoardConfig.mk

@@ -89,6 +89,11 @@ BOARD_LISA_TARGET_SCRIPTS := device/google/wahoo/lisa/
 # rounded_corner_radius in overlay/frameworks/base/packages/SystemUI/res/values/dimens.xml.
 TARGET_RECOVERY_UI_MARGIN_HEIGHT := 105
 
+TARGET_RECOVERY_UI_LIB := \
+    librecovery_ui_taimen \
+    libbootloader_message \
+    libfstab
+
 # VTS DTBO Verification. This kernel cmdline parameter should be added by the bootloader
 # for all future devices.
 BOARD_KERNEL_CMDLINE += androidboot.dtbo_idx=12

init-taimen.rc

@@ -52,3 +52,27 @@ on late-init && property:ro.boot.revision=rev_a
 
 on late-init && property:ro.boot.revision=rev_b
     setprop vendor.thermal.config thermal_info_config_evt.json
+
+# Write the dark theme magic (`theme-dark`, or 0x7468656d652d6461726b in hex string) to /misc
+# partition. Offset 0 in vendor space is effectively offset 2048 in /misc partition.
+service vendor.theme_set /vendor/bin/misc_writer --vendor-space-offset 0 --hex-string 0x7468656d652d6461726b
+    disabled
+    oneshot
+
+# Clear the 10-byte dark theme magic in /misc partition. Offset 0 in vendor space is effectively
+# offset 2048 in /misc partition.
+service vendor.theme_clear /vendor/bin/misc_writer --vendor-space-offset 0 --hex-string 0x00000000000000000000
+    disabled
+    oneshot
+
+# Set the dark boot flag on dark mode (UiModeManager.MODE_NIGHT_YES == 2).
+on property:persist.sys.theme=2
+    start vendor.theme_set
+
+# Clear the dark theme flag on light mode (UiModeManager.MODE_NIGHT_NO == 1) or auto mode
+# (UiModeManager.MODE_NIGHT_AUTO == 0).
+on property:persist.sys.theme=1
+    start vendor.theme_clear
+
+on property:persist.sys.theme=0
+    start vendor.theme_clear

recovery/Android.bp

@@ -0,0 +1,38 @@
+//
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+cc_library_static {
+    name: "librecovery_ui_taimen",
+    owner: "google",
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+        "-pedantic",
+    ],
+    srcs: [
+        "recovery_ui.cpp",
+    ],
+
+    static_libs: [
+        "libbootloader_message",
+    ],
+
+    shared_libs: [
+        "libbase",
+        "librecovery_ui",
+    ],
+}

recovery/recovery_ui.cpp

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string>
+
+#include <android-base/logging.h>
+#include <bootloader_message/bootloader_message.h>
+#include <recovery_ui/device.h>
+#include <recovery_ui/screen_ui.h>
+
+// Wipes the provisioned flag as part of data wipe.
+static bool WipeProvisionedFlag() {
+    // Must be consistent with the one in init.hardware.rc (10-byte `theme-dark`).
+    const std::string wipe_str(10, '\x00');
+    constexpr size_t kProvisionedFlagOffsetInVendorSpace = 0;
+    if (std::string err; !WriteMiscPartitionVendorSpace(
+            wipe_str.data(), wipe_str.size(), kProvisionedFlagOffsetInVendorSpace, &err)) {
+        LOG(ERROR) << "Failed to write wipe string: " << err;
+        return false;
+    }
+    LOG(INFO) << "Provisioned flag wiped successful";
+    return true;
+}
+
+class TaimenDevice : public Device {
+  public:
+    TaimenDevice(ScreenRecoveryUI* ui) : Device(ui) {}
+
+    // Hook to wipe user data not stored in /data.
+    bool PostWipeData() override {
+        // Try to do everything but report a failure if anything wasn't successful.
+        bool total_success = true;
+        auto ui = GetUI();
+        ui->Print("Wiping provisioned flag...\n");
+        if (!WipeProvisionedFlag()) {
+            total_success = false;
+        }
+        return total_success;
+    }
+};
+
+Device* make_device() {
+    return new TaimenDevice(new ScreenRecoveryUI);
+}