update_engine resize dynamic partitions during OTA.

update_engine uses device mapper to resize dynamic partitions
before opening the devices to apply the update.

* DeltaPerformer calls BootControlInterface::InitPartitionMetadata
  when parsing the update manifest. The implementation for
  BootControlAndroid::InitPartitionMetadata does the following
  if sizes for dynamic partitions are incorrect (assuming updating
  from slot A to B):
  * Load metadata from metadata slot A
  * Delete all extents of partitions at slot B (with _b suffix)
  * Add extents for partitions at slot B
  * Write metadata to metadata slot B
  * Re-map all partitions at slot B using metadata slot B with
    force_writable = true
* BootControlAndroid::GetPartitionDevice() checks device-mapper
  before returning static partitions.
* PostinstallRunnerAction::Cleanup calls BootControlInterface::Cleanup
  which unmaps all partitions at slot B.

A partition "foo" is considered dynamic if foo_a exists as a dynamic
partition OR foo_b does NOT exist as a static partition.

Bug: 110717529

Test: manual ota
Test: update_engine_unittests --gtest_filter=*BootControlAndroid*
Change-Id: I50f410b486a874242663624801c3694151bdda18
diff --git a/boot_control_recovery.cc b/boot_control_recovery.cc
index 722d32a..c6e3ffd 100644
--- a/boot_control_recovery.cc
+++ b/boot_control_recovery.cc
@@ -183,4 +183,18 @@
          brillo::MessageLoop::kTaskIdNull;
 }
 
+// TODO(b/78598708): Remove BootControlRecovery, so don't bother resizing
+// partitions here.
+bool BootControlRecovery::InitPartitionMetadata(
+    Slot slot, const PartitionSizes& partition_sizes) {
+  LOG(ERROR) << __FUNCTION__
+             << " is not implemented. BootControlRecovery will be removed.";
+  return true;
+}
+
+void BootControlRecovery::Cleanup() {
+  LOG(ERROR) << __FUNCTION__
+             << " is not implemented. BootControlRecovery will be removed.";
+}
+
 }  // namespace chromeos_update_engine