Build API: Add logic to handle toolchain changes

Updated chromite build API protos to include new toolchain_change field

BUG=b:147589410
TEST=None

Change-Id: I51eafa718d3e59ab6abe78d5873f43670fb064a8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1997261
Tested-by: Chris McDonald <cjmcdonald@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
Auto-Submit: Chris McDonald <cjmcdonald@chromium.org>
diff --git a/api/controller/sdk.py b/api/controller/sdk.py
index f017fd9..60f5a96 100644
--- a/api/controller/sdk.py
+++ b/api/controller/sdk.py
@@ -72,9 +72,13 @@
   """
   build_source = input_proto.flags.build_source
   targets = [target.name for target in input_proto.toolchain_targets]
+  toolchain_changed = input_proto.flags.toolchain_changed
 
-  args = sdk.UpdateArguments(build_source=build_source,
-                             toolchain_targets=targets)
+  args = sdk.UpdateArguments(
+      build_source=build_source,
+      toolchain_targets=targets,
+      toolchain_changed=toolchain_changed)
+
   version = sdk.Update(args)
 
   if version: