Notify UKM scheduler of RotationFinished.

Bug:812729

TBR=holte@google.com

(cherry picked from commit 0a8bf4c52054b40a9160b0db5031aae34ecbda07)

Change-Id: I418d2b540302805c08f78d63635f394f02fe3ac5
Reviewed-on: https://chromium-review.googlesource.com/922722
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#537131}
Reviewed-on: https://chromium-review.googlesource.com/927750
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/branch-heads/3325@{#521}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
diff --git a/components/ukm/ukm_service.cc b/components/ukm/ukm_service.cc
index 90a43fc..31bb4a2 100644
--- a/components/ukm/ukm_service.cc
+++ b/components/ukm/ukm_service.cc
@@ -221,6 +221,7 @@
   if (!reporting_service_.ukm_log_store()->has_unsent_logs())
     BuildAndStoreLog();
   reporting_service_.Start();
+  scheduler_->RotationFinished();
 }
 
 void UkmService::BuildAndStoreLog() {