This component contains the code for MetricsService and supporting code, which
is used for UMA reporting and for other metrics services like UKM.

The main component aims to have a minimal set of dependencies and in particular
does not depend on //net or //content.

Files depending on //net or //content are placed in separate subdirectories:
//components/metrics/net and //components/metrics/content, respectively.

Additional subdirectories exist to provide specific functionality, for example
//components/metrics/structured for Structured Metrics and
//components/metrics/serialization for a ChromeOS serialization mechanism.