SF: DisplayCommand.colorTransform is just a matrix

Remove the hint from DisplayCommand.colorTransform as currently
we only use ColorTransform::IDENTITY and ColorTransform::ARBITRARY_MATRIX,
which both can be expressed using a matrix.

Bug: 208879711
Test: VTS
Change-Id: I1c335647aabb7f89c2c89e54abfc839d10a659fb
diff --git a/services/surfaceflinger/tests/unittests/CompositionTest.cpp b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
index 7174f58..89a517f 100644
--- a/services/surfaceflinger/tests/unittests/CompositionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/CompositionTest.cpp
@@ -87,6 +87,11 @@
 
 constexpr int DEFAULT_SIDEBAND_STREAM = 51;
 
+MATCHER(IsIdentityMatrix, "") {
+    constexpr auto kIdentity = mat4();
+    return (mat4(arg) == kIdentity);
+}
+
 class CompositionTest : public testing::Test {
 public:
     CompositionTest() {
@@ -325,9 +330,7 @@
 
     template <typename Case>
     static void setupCommonCompositionCallExpectations(CompositionTest* test) {
-        EXPECT_CALL(*test->mComposer,
-                    setColorTransform(HWC_DISPLAY, _, Hwc2::ColorTransform::IDENTITY))
-                .Times(1);
+        EXPECT_CALL(*test->mComposer, setColorTransform(HWC_DISPLAY, IsIdentityMatrix())).Times(1);
         EXPECT_CALL(*test->mComposer, getDisplayRequests(HWC_DISPLAY, _, _, _)).Times(1);
         EXPECT_CALL(*test->mComposer, acceptDisplayChanges(HWC_DISPLAY)).Times(1);
         EXPECT_CALL(*test->mComposer, presentDisplay(HWC_DISPLAY, _)).Times(1);
@@ -448,9 +451,7 @@
     template <typename Case>
     static void setupCommonCompositionCallExpectations(CompositionTest* test) {
         // TODO: This seems like an unnecessary call if display is powered off.
-        EXPECT_CALL(*test->mComposer,
-                    setColorTransform(HWC_DISPLAY, _, Hwc2::ColorTransform::IDENTITY))
-                .Times(1);
+        EXPECT_CALL(*test->mComposer, setColorTransform(HWC_DISPLAY, IsIdentityMatrix())).Times(1);
 
         // TODO: This seems like an unnecessary call if display is powered off.
         Case::CompositionType::setupHwcSetCallExpectations(test);