NeedsChromeSource: Minor fixes.

The USE flag handling in the controller was not correct.
The build target depgraph was an unnecessarily wide net, only
the sysroot depgraph is needed to check for chrome requirements.

BUG=chromium:1086714
TEST=manually ran endpoint

Change-Id: Ifd6ab36af2e6aa95beba609285826a4ac08506a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2676824
Tested-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Alex Klein <saklein@chromium.org>
Reviewed-by: Michael Mortensen <mmortensen@google.com>
diff --git a/service/packages_unittest.py b/service/packages_unittest.py
index 67484bd..33b8d04 100644
--- a/service/packages_unittest.py
+++ b/service/packages_unittest.py
@@ -1126,7 +1126,7 @@
   def test_needs_all(self):
     """Verify we need source when we have no prebuilts."""
     graph = self._build_graph(with_chrome=True, with_followers=True)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=False)
 
@@ -1145,7 +1145,7 @@
   def test_needs_none(self):
     """Verify not building any of the chrome packages prevents needing it."""
     graph = self._build_graph(with_chrome=False, with_followers=False)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=False)
 
@@ -1162,7 +1162,7 @@
   def test_needs_chrome_only(self):
     """Verify only chrome triggers needs chrome source."""
     graph = self._build_graph(with_chrome=True, with_followers=False)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=False)
 
@@ -1181,7 +1181,7 @@
   def test_needs_followers_only(self):
     """Verify only chrome followers triggers needs chrome source."""
     graph = self._build_graph(with_chrome=False, with_followers=True)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=False)
 
@@ -1200,7 +1200,7 @@
   def test_has_prebuilts(self):
     """Test prebuilts prevent us from needing chrome source."""
     graph = self._build_graph(with_chrome=True, with_followers=True)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=True)
 
@@ -1217,7 +1217,7 @@
   def test_compile_source(self):
     """Test compile source ignores prebuilts."""
     graph = self._build_graph(with_chrome=True, with_followers=True)
-    self.PatchObject(depgraph, 'get_build_target_dependency_graph',
+    self.PatchObject(depgraph, 'get_sysroot_dependency_graph',
                      return_value=graph)
     self.PatchObject(packages, 'has_prebuilt', return_value=True)