image_lib: move GetImageDiskPartitionInfo from cros_build_lib

This fits better with the image_lib code that cros_build_lib, so move
it out to that module.  The few callers of this are largely already
utilizing image_lib, and having to parse disk image info is pretty
uncommon operation (compared to cros_build_lib).

BUG=chromium:868820
TEST=unittests pass

Change-Id: Ib7f6a96f05b2884416993f416f4ddac827666cd0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1816925
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/test_image_unittest.py b/scripts/test_image_unittest.py
index 67b861c..5f71285 100644
--- a/scripts/test_image_unittest.py
+++ b/scripts/test_image_unittest.py
@@ -12,7 +12,6 @@
 import unittest
 
 from chromite.lib import constants
-from chromite.lib import cros_build_lib
 from chromite.lib import cros_test_lib
 from chromite.lib import image_lib
 from chromite.lib import image_test_lib
@@ -32,11 +31,11 @@
                                    constants.BASE_IMAGE_NAME + '.bin')
     osutils.WriteFile(self.image_file, '')
     fake_partitions = (
-        cros_build_lib.PartitionInfo(1, 0, 0, 0, 'fs', 'STATE', 'flag'),
-        cros_build_lib.PartitionInfo(2, 0, 0, 0, 'fs', 'KERN-A', 'flag'),
-        cros_build_lib.PartitionInfo(3, 0, 0, 0, 'fs', 'ROOT-A', 'flag'),
+        image_lib.PartitionInfo(1, 0, 0, 0, 'fs', 'STATE', 'flag'),
+        image_lib.PartitionInfo(2, 0, 0, 0, 'fs', 'KERN-A', 'flag'),
+        image_lib.PartitionInfo(3, 0, 0, 0, 'fs', 'ROOT-A', 'flag'),
     )
-    self.PatchObject(cros_build_lib, 'GetImageDiskPartitionInfo',
+    self.PatchObject(image_lib, 'GetImageDiskPartitionInfo',
                      autospec=True, return_value=fake_partitions)
     self.PatchObject(image_lib.LoopbackPartitions, '_Mount', autospec=True)
     self.PatchObject(image_lib.LoopbackPartitions, '_Unmount', autospec=True)