Code clean for libcameraservice

Cleaning compile warnings "variable 'XX' set but not used":
1. Remove the variables which are obviously not used;
2. Add "[[maybe_unused]]" to variable declaration of the ones
   which are potentially used.

For the unused function parameters which were cast by "(void)":
We have changed them to the C++17 attribute "[[maybe_unused]]".
This seems not that necessary but it avoids redundant code lines.

Test: mmm frameworks/av/services/camera/libcameraservice,
      presubmit check.

Change-Id: Ia68b78c01f8254d76be81b1ce98d2a5c3d7eea46
Signed-off-by: Jing Mike <jingyangliu@eswincomputing.com>
diff --git a/services/camera/libcameraservice/common/Camera2ClientBase.cpp b/services/camera/libcameraservice/common/Camera2ClientBase.cpp
index ad24392..71d0f9e 100644
--- a/services/camera/libcameraservice/common/Camera2ClientBase.cpp
+++ b/services/camera/libcameraservice/common/Camera2ClientBase.cpp
@@ -380,50 +380,38 @@
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyShutter(const CaptureResultExtras& resultExtras,
-                                                   nsecs_t timestamp) {
-    (void)resultExtras;
-    (void)timestamp;
-
+void Camera2ClientBase<TClientBase>::notifyShutter(
+                [[maybe_unused]] const CaptureResultExtras& resultExtras,
+                [[maybe_unused]] nsecs_t timestamp) {
     ALOGV("%s: Shutter notification for request id %" PRId32 " at time %" PRId64,
             __FUNCTION__, resultExtras.requestId, timestamp);
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyAutoFocus(uint8_t newState,
-                                                     int triggerId) {
-    (void)newState;
-    (void)triggerId;
-
+void Camera2ClientBase<TClientBase>::notifyAutoFocus([[maybe_unused]] uint8_t newState,
+                                                     [[maybe_unused]] int triggerId) {
     ALOGV("%s: Autofocus state now %d, last trigger %d",
           __FUNCTION__, newState, triggerId);
 
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyAutoExposure(uint8_t newState,
-                                                        int triggerId) {
-    (void)newState;
-    (void)triggerId;
-
+void Camera2ClientBase<TClientBase>::notifyAutoExposure([[maybe_unused]] uint8_t newState,
+                                                        [[maybe_unused]] int triggerId) {
     ALOGV("%s: Autoexposure state now %d, last trigger %d",
             __FUNCTION__, newState, triggerId);
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyAutoWhitebalance(uint8_t newState,
-                                                            int triggerId) {
-    (void)newState;
-    (void)triggerId;
-
+void Camera2ClientBase<TClientBase>::notifyAutoWhitebalance(
+                [[maybe_unused]] uint8_t newState,
+                [[maybe_unused]] int triggerId) {
     ALOGV("%s: Auto-whitebalance state now %d, last trigger %d",
             __FUNCTION__, newState, triggerId);
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyPrepared(int streamId) {
-    (void)streamId;
-
+void Camera2ClientBase<TClientBase>::notifyPrepared([[maybe_unused]] int streamId) {
     ALOGV("%s: Stream %d now prepared",
             __FUNCTION__, streamId);
 }
@@ -435,9 +423,8 @@
 }
 
 template <typename TClientBase>
-void Camera2ClientBase<TClientBase>::notifyRepeatingRequestError(long lastFrameNumber) {
-    (void)lastFrameNumber;
-
+void Camera2ClientBase<TClientBase>::notifyRepeatingRequestError(
+            [[maybe_unused]] long lastFrameNumber) {
     ALOGV("%s: Repeating request was stopped. Last frame number is %ld",
             __FUNCTION__, lastFrameNumber);
 }
diff --git a/services/camera/libcameraservice/common/CameraProviderManager.cpp b/services/camera/libcameraservice/common/CameraProviderManager.cpp
index 3aab0b1..c72986d 100644
--- a/services/camera/libcameraservice/common/CameraProviderManager.cpp
+++ b/services/camera/libcameraservice/common/CameraProviderManager.cpp
@@ -1858,13 +1858,12 @@
 CameraProviderManager::ProviderInfo::ProviderInfo(
         const std::string &providerName,
         const std::string &providerInstance,
-        CameraProviderManager *manager) :
+        [[maybe_unused]] CameraProviderManager *manager) :
         mProviderName(providerName),
         mProviderInstance(providerInstance),
         mProviderTagid(generateVendorTagId(providerName)),
         mUniqueDeviceCount(0),
         mManager(manager) {
-    (void) mManager;
 }
 
 const std::string& CameraProviderManager::ProviderInfo::getType() const {
diff --git a/services/camera/libcameraservice/common/CameraProviderManager.h b/services/camera/libcameraservice/common/CameraProviderManager.h
index e8d9a37..8d60afd 100644
--- a/services/camera/libcameraservice/common/CameraProviderManager.h
+++ b/services/camera/libcameraservice/common/CameraProviderManager.h
@@ -572,17 +572,15 @@
                     hardware::CameraInfo *info) const = 0;
             virtual bool isAPI1Compatible() const = 0;
             virtual status_t dumpState(int fd) = 0;
-            virtual status_t getCameraCharacteristics(bool overrideForPerfClass,
-                    CameraMetadata *characteristics, bool overrideToPortrait) {
-                (void) overrideForPerfClass;
-                (void) characteristics;
-                (void) overrideToPortrait;
+            virtual status_t getCameraCharacteristics(
+                    [[maybe_unused]] bool overrideForPerfClass,
+                    [[maybe_unused]] CameraMetadata *characteristics,
+                    [[maybe_unused]] bool overrideToPortrait) {
                 return INVALID_OPERATION;
             }
-            virtual status_t getPhysicalCameraCharacteristics(const std::string& physicalCameraId,
-                    CameraMetadata *characteristics) const {
-                (void) physicalCameraId;
-                (void) characteristics;
+            virtual status_t getPhysicalCameraCharacteristics(
+                    [[maybe_unused]] const std::string& physicalCameraId,
+                    [[maybe_unused]] CameraMetadata *characteristics) const {
                 return INVALID_OPERATION;
             }
 
diff --git a/services/camera/libcameraservice/common/hidl/HidlProviderInfo.cpp b/services/camera/libcameraservice/common/hidl/HidlProviderInfo.cpp
index 15aa5a5..fec7f05 100644
--- a/services/camera/libcameraservice/common/hidl/HidlProviderInfo.cpp
+++ b/services/camera/libcameraservice/common/hidl/HidlProviderInfo.cpp
@@ -442,8 +442,7 @@
 }
 
 void HidlProviderInfo::serviceDied(uint64_t cookie,
-        const wp<hidl::base::V1_0::IBase>& who) {
-    (void) who;
+        [[maybe_unused]] const wp<hidl::base::V1_0::IBase>& who) {
     ALOGI("Camera provider '%s' has died; removing it", mProviderInstance.c_str());
     if (cookie != mId) {
         ALOGW("%s: Unexpected serviceDied cookie %" PRIu64 ", expected %" PRIu32,