Control data saver pingback reporting fraction with protobuf

components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc
index 7d9c06677493de75f21c90f96e201eebe640bb9a..50796496e8eaf9545c77f6be607a34b2b68b9c99 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.cc
@@ -1,16 +1,17 @@
 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_pingback_client.h"
 
+#include "base/rand_util.h"
 #include "components/data_reduction_proxy/core/browser/data_reduction_proxy_data.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_page_load_timing.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_params.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_util.h"
 #include "components/data_reduction_proxy/proto/client_config.pb.h"
 #include "components/data_reduction_proxy/proto/pageload_metrics.pb.h"
 #include "net/base/load_flags.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_status.h"
@@ -58,21 +59,22 @@ std::string SerializeData(const DataReductionProxyData& request_data,
   std::string serialized_request;
   batched_request.SerializeToString(&serialized_request);
   return serialized_request;
 }
 
 }  // namespace
 
 DataReductionProxyPingbackClient::DataReductionProxyPingbackClient(
     net::URLRequestContextGetter* url_request_context)
     : url_request_context_(url_request_context),
-      pingback_url_(util::AddApiKeyToUrl(params::GetPingbackURL())) {}
+      pingback_url_(util::AddApiKeyToUrl(params::GetPingbackURL())),
+      pingback_reporting_fraction_(0.0) {}
 
 DataReductionProxyPingbackClient::~DataReductionProxyPingbackClient() {
   DCHECK(thread_checker_.CalledOnValidThread());
 }
 
 void DataReductionProxyPingbackClient::OnURLFetchComplete(
     const net::URLFetcher* source) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(source == current_fetcher_.get());
   // TODO(ryansturm): Add UMA to measure failures. crbug.com/616544
@@ -109,16 +111,27 @@ DataReductionProxyPingbackClient::MaybeCreateFetcherForDataAndStart(
   fetcher->SetRequestContext(url_request_context_);
   // Configure max retries to be at most kMaxRetries times for 5xx errors.
   static const int kMaxRetries = 5;
   fetcher->SetMaxRetriesOn5xx(kMaxRetries);
   fetcher->SetAutomaticallyRetryOnNetworkChanges(kMaxRetries);
   fetcher->Start();
   return fetcher;
 }
 
 bool DataReductionProxyPingbackClient::ShouldSendPingback() const {
-  // TODO(ryansturm): Modulate the frequency of sending a pingback based on a
-  // client config parameter. crbug.com/616805
-  return params::IsForcePingbackEnabledViaFlags();
+  return params::IsForcePingbackEnabledViaFlags() ||
+         GenerateRandomFloat() < pingback_reporting_fraction_;
+}
+
+float DataReductionProxyPingbackClient::GenerateRandomFloat() const {
+  return static_cast<float>(base::RandDouble());
+}
+
+void DataReductionProxyPingbackClient::SetPingbackReportingFraction(
+    float pingback_reporting_fraction) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_LE(0.0f, pingback_reporting_fraction);
+  DCHECK_GE(1.0f, pingback_reporting_fraction);
+  pingback_reporting_fraction_ = pingback_reporting_fraction;
 }
 
 }  // namespace data_reduction_proxy