Fix flaky CountingPolicyTest.CapReturns test

chrome/browser/extensions/activity_log/counting_policy_unittest.cc

Index: chrome/browser/extensions/activity_log/counting_policy_unittest.cc
diff --git a/chrome/browser/extensions/activity_log/counting_policy_unittest.cc b/chrome/browser/extensions/activity_log/counting_policy_unittest.cc
index d71feaf687ab09243ecfe593b58af5f6abbb8026..c11f14854201295743f46412bd9fc05c87360959 100644
--- a/chrome/browser/extensions/activity_log/counting_policy_unittest.cc
+++ b/chrome/browser/extensions/activity_log/counting_policy_unittest.cc
@@ -124,12 +124,12 @@ class CountingPolicyTest : public testing::Test {
                    checker,
                    base::MessageLoop::current()->QuitClosure()));
 
-    // Set up a timeout that will trigger after 5 seconds; if we haven't
+    // Set up a timeout that will trigger after 8 seconds; if we haven't
     // received any results by then assume that the test is broken.
     base::CancelableClosure timeout(
         base::Bind(&CountingPolicyTest::TimeoutCallback));
     base::MessageLoop::current()->PostDelayedTask(
-        FROM_HERE, timeout.callback(), base::TimeDelta::FromSeconds(5));
+        FROM_HERE, timeout.callback(), base::TimeDelta::FromSeconds(8));
 
     // Wait for results; either the checker or the timeout callbacks should
     // cause the main loop to exit.
@@ -798,7 +798,9 @@ TEST_F(CountingPolicyTest, CapReturns) {
                    base::StringPrintf("apicall_%d", i));
     policy->ProcessAction(action);
   }
+
   policy->Flush();
+  WaitOnThread(BrowserThread::DB);
 
   CheckReadFilteredData(
       policy,