Added completion notification to Profile's ClearNetworkingHistorySince.

chrome/browser/browsing_data/browsing_data_remover_browsertest.cc

Index: chrome/browser/browsing_data/browsing_data_remover_browsertest.cc
diff --git a/chrome/browser/browsing_data/browsing_data_remover_browsertest.cc b/chrome/browser/browsing_data/browsing_data_remover_browsertest.cc
index a34cfe7bd6670f2564dc8dbde6e46dd5490bd768..c8390b62bbd5f2d4dc7b1ba7ca71539e44813034 100644
--- a/chrome/browser/browsing_data/browsing_data_remover_browsertest.cc
+++ b/chrome/browser/browsing_data/browsing_data_remover_browsertest.cc
@@ -112,3 +112,8 @@ IN_PROC_BROWSER_TEST_F(BrowsingDataRemoverBrowserTest, Database) {
   RunScriptAndCheckResult(L"insertRecord('text2')", "done");
   RunScriptAndCheckResult(L"getRecords()", "text2");
 }
+
+// Profile::ClearNetworkingHistorySince should be exercised here too see whether
+// the call gets delegated through ProfileIO[Impl]Data properly, which is hard
+// to write unit-tests for. Currently this is done by both of the above tests.
+// Add standalone test if this changes.