Domain Reliability: Add sample_rate field to Beacon

components/domain_reliability/context_unittest.cc

Index: components/domain_reliability/context_unittest.cc
diff --git a/components/domain_reliability/context_unittest.cc b/components/domain_reliability/context_unittest.cc
index 5b42d2187b50a1849d398f5c9bf890df4d07e5b9..a78d43376a9b1b3d50ba0263bdcab4b5874685b0 100644
--- a/components/domain_reliability/context_unittest.cc
+++ b/components/domain_reliability/context_unittest.cc
@@ -36,6 +36,7 @@ scoped_ptr<DomainReliabilityBeacon> MakeBeacon(MockableTime* time) {
   beacon->elapsed = base::TimeDelta::FromMilliseconds(250);
   beacon->start_time = time->NowTicks() - beacon->elapsed;
   beacon->upload_depth = 0;
+  beacon->sample_rate = 1.0;
   return beacon.Pass();
 }
 
@@ -214,10 +215,10 @@ TEST_F(DomainReliabilityContextTest, ReportUpload) {
       "{\"failure_data\":{\"custom_error\":\"net::ERR_CONNECTION_RESET\"},"
       "\"network_changed\":false,\"protocol\":\"HTTP\","
       "\"quic_broken\":true,\"request_age_ms\":300250,"
-      "\"request_elapsed_ms\":250,"
+      "\"request_elapsed_ms\":250,\"sample_rate\":1.0,"
       "\"server_ip\":\"127.0.0.1\",\"status\":\"tcp.connection_reset\","
-      "\"url\":\"https://localhost/\","
-      "\"was_proxied\":false}],\"reporter\":\"test-reporter\"}";
+      "\"url\":\"https://localhost/\",\"was_proxied\":false}],"
+      "\"reporter\":\"test-reporter\"}";
 
   time_.Advance(max_delay());
   EXPECT_TRUE(upload_pending());
@@ -245,10 +246,10 @@ TEST_F(DomainReliabilityContextTest, Upload_NetworkChanged) {
       "{\"failure_data\":{\"custom_error\":\"net::ERR_CONNECTION_RESET\"},"
       "\"network_changed\":true,\"protocol\":\"HTTP\","
       "\"quic_broken\":true,\"request_age_ms\":300250,"
-      "\"request_elapsed_ms\":250,"
+      "\"request_elapsed_ms\":250,\"sample_rate\":1.0,"

[jkarlin, 2015/12/09 11:46:22]

Needs more tests. Include rates such as 0.0, 1.0, 0.33, and out of bounds checks
like -5 and 50. Also, shouldn't there be tests for success sample rates and
failure sample rates?

[Deprecated (see juliatuttle), 2015/12/10 17:04:23]

I've added tests for 0.0 and 0.5 (1.0 is tested implicitly, as it's the default
in the tests).

Out of bounds checks are handled before the Config gets here. Right now,
anything negative behaves as if it's 0.0, and anything above 1.0 behaves as if
it's 1.0. Does that seem reasonable, and does it need explicit testing?

       "\"server_ip\":\"127.0.0.1\",\"status\":\"tcp.connection_reset\","
-      "\"url\":\"https://localhost/\","
-      "\"was_proxied\":false}],\"reporter\":\"test-reporter\"}";
+      "\"url\":\"https://localhost/\",\"was_proxied\":false}],"
+      "\"reporter\":\"test-reporter\"}";
 
   // Simulate a network change after the request but before the upload.
   last_network_change_time_ = time_.NowTicks();