Fix clang-tidy warnings in camera.

* Add explicit keyword to conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
* Use const reference type to avoid unnecessary copy.
Bug: 30413862
Test: build with WITH_TIDY=1

Change-Id: I71d3008da843ba5f1df1a73a320fb2af6ceffa16
Merged-In: I71d3008da843ba5f1df1a73a320fb2af6ceffa16
diff --git a/services/camera/libcameraservice/CameraService.h b/services/camera/libcameraservice/CameraService.h
index ec8c5e9..269507e 100644
--- a/services/camera/libcameraservice/CameraService.h
+++ b/services/camera/libcameraservice/CameraService.h
@@ -265,7 +265,7 @@
 
         class OpsCallback : public BnAppOpsCallback {
         public:
-            OpsCallback(wp<BasicClient> client);
+            explicit OpsCallback(wp<BasicClient> client);
             virtual void opChanged(int32_t op, const String16& packageName);
 
         private: