Adding DataReductionProxy (DRP) specfic UMA for FirstContentfulPaint.
This consumes the PageLoad.Timing2 code path to get data specific to DRP with regards to having DRP on and being in the lofi experiment. Right now, it only considers
NavigationToFirstContentfulPaint.
This introduces:
DataReductionProxyData, which is stored on URLRequest;
NavigationData, a cloneable interface used in content/ to communicate information to NavigationHandle;
ChromeNavigationData, an inheritor of NavigationData that owns a DataReductionProxyData and is stored in NavigationHandleImpl (UI thread) and URLRequest (IO thread, in UserData).
BUG=578321
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation
Review-Url: https://codereview.chromium.org/1721813002
Cr-Commit-Position: refs/heads/master@{#393087}
50 files changed
