clang/win: Fix component build after https://codereview.chromium.org/1149383004/

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

Committed: https://crrev.com/2490eae99cb38140e27dcb3e89fb21385a84f676
Cr-Commit-Position: refs/heads/master@{#334995}

[Nico, 2015-06-18 04:04:34]

thakis@chromium.org changed reviewers:
+ hans@chromium.org, horo@chromium.org

[Nico, 2015-06-18 04:04:39]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-06-18 04:05:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1192653002/1

[horo, 2015-06-18 04:09:50]

lgtm

[commit-bot: I haz the power, 2015-06-18 05:21:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-18 05:22:37]

Patchset 1 (id:??) landed as
https://crrev.com/2490eae99cb38140e27dcb3e89fb21385a84f676
Cr-Commit-Position: refs/heads/master@{#334995}

[hans, 2015-06-18 15:50:33]

lgtm