Fix clang-tidy warnings in mediaresourcemanager.

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

Change-Id: I9aac64b379ddb77a9abb4b03a6648f38e2a756ab
Merged-In: I9aac64b379ddb77a9abb4b03a6648f38e2a756ab
4 files changed