handle multiple cas plugins.
some of them support descrambler, some of them don't

bug: 176799453
Test: atest VtsHalCasV1_[#]TargetTest
Change-Id: Ifec298486b413129601787755bbe8e7bbea6cbf3
diff --git a/cas/1.2/vts/functional/VtsHalCasV1_2TargetTest.cpp b/cas/1.2/vts/functional/VtsHalCasV1_2TargetTest.cpp
index 333dea6..0d75f5b 100644
--- a/cas/1.2/vts/functional/VtsHalCasV1_2TargetTest.cpp
+++ b/cas/1.2/vts/functional/VtsHalCasV1_2TargetTest.cpp
@@ -311,7 +311,6 @@
     sp<ICas> mMediaCas;
     sp<IDescramblerBase> mDescramblerBase;
     sp<MediaCasListener> mCasListener;
-    bool mIsTestDescrambler = false;
     typedef struct _OobInputTestParams {
         const SubSample* subSamples;
         uint32_t numSubSamples;
@@ -336,12 +335,15 @@
 
 ::testing::AssertionResult MediaCasHidlTest::createCasPlugin(int32_t caSystemId) {
     auto status = mService->isSystemIdSupported(caSystemId);
+    bool skipDescrambler = false;
     if (!status.isOk() || !status) {
         return ::testing::AssertionFailure();
     }
     status = mService->isDescramblerSupported(caSystemId);
     if (!status.isOk() || !status) {
-        return ::testing::AssertionFailure();
+        ALOGI("Skip Descrambler test since it's not required in cas@1.2.");
+        mDescramblerBase = nullptr;
+        skipDescrambler = true;
     }
 
     mCasListener = new MediaCasListener();
@@ -354,12 +356,14 @@
         return ::testing::AssertionFailure();
     }
 
-    auto descramblerStatus = mService->createDescrambler(caSystemId);
-    if (!descramblerStatus.isOk()) {
-        ALOGI("Skip Descrambler test since it's not required in cas@1.2.");
+    if (skipDescrambler) {
         return ::testing::AssertionSuccess();
     }
-    mIsTestDescrambler = true;
+
+    auto descramblerStatus = mService->createDescrambler(caSystemId);
+    if (!descramblerStatus.isOk()) {
+        return ::testing::AssertionFailure();
+    }
 
     mDescramblerBase = descramblerStatus;
     return ::testing::AssertionResult(mDescramblerBase != nullptr);
@@ -516,7 +520,7 @@
     EXPECT_TRUE(returnStatus.isOk());
     EXPECT_EQ(Status::OK, returnStatus);
 
-    if (mIsTestDescrambler) {
+    if (mDescramblerBase != nullptr) {
         returnStatus = mDescramblerBase->setMediaCasSession(sessionId);
         EXPECT_TRUE(returnStatus.isOk());
         EXPECT_EQ(Status::OK, returnStatus);
@@ -571,7 +575,7 @@
     EXPECT_TRUE(returnStatus.isOk());
     EXPECT_EQ(Status::OK, returnStatus);
 
-    if (mIsTestDescrambler) {
+    if (mDescramblerBase != nullptr) {
         EXPECT_FALSE(mDescramblerBase->requiresSecureDecoderComponent("video/avc"));
 
         sp<IDescrambler> descrambler;