clang/win: Fix component build after https://codereview.chromium.org/
1149383004/
The compiler may choose to inline ServiceWorkerVersionInfo's assignment
operator in clients. The assignment operator needs to assign ClientInfo
objects in the clients map<>, which can call ~ClientInfo(). So ClientInfo needs
to be exported, as it can be referenced from outside content this way.
BUG=82385,466871
TBR=hans,horo
Review URL: https://codereview.chromium.org/
1192653002
Cr-Commit-Position: refs/heads/master@{#334995}