Implementation of network level throttler.

net/http/http_network_transaction.h

Index: net/http/http_network_transaction.h
diff --git a/net/http/http_network_transaction.h b/net/http/http_network_transaction.h
index f95cd36d8219d5ab7f77dccb466d1657e8ce31b8..d8638aa276f4d45a50941a2febe7a1fec9aa4682 100644
--- a/net/http/http_network_transaction.h
+++ b/net/http/http_network_transaction.h
@@ -16,6 +16,7 @@
 #include "base/time/time.h"
 #include "crypto/ec_private_key.h"
 #include "net/base/net_error_details.h"
+#include "net/base/network_stream_throttler.h"
 #include "net/base/request_priority.h"
 #include "net/http/http_auth.h"
 #include "net/http/http_request_headers.h"
@@ -50,7 +51,8 @@ struct HttpRequestInfo;
 
 class NET_EXPORT_PRIVATE HttpNetworkTransaction
     : public HttpTransaction,
-      public HttpStreamRequest::Delegate {
+      public HttpStreamRequest::Delegate,
+      public NetworkStreamThrottler::Delegate {
  public:
   HttpNetworkTransaction(RequestPriority priority,
                          HttpNetworkSession* session);
@@ -124,6 +126,9 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   void OnQuicBroken() override;
   void GetConnectionAttempts(ConnectionAttempts* out) const override;
 
+  // NetworkStreamThrottler::Delegate methods:
+  void OnThrottleStateChanged() override;
+
  private:
   friend class HttpNetworkTransactionSSLTest;
 
@@ -145,6 +150,8 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
                            FlowControlNegativeSendWindowSize);
 
   enum State {
+    STATE_THROTTLE,
+    STATE_THROTTLE_COMPLETE,
     STATE_NOTIFY_BEFORE_CREATE_STREAM,
     STATE_CREATE_STREAM,
     STATE_CREATE_STREAM_COMPLETE,
@@ -191,6 +198,8 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   // argument receive the result from the previous state.  If a method returns
   // ERR_IO_PENDING, then the result from OnIOComplete will be passed to the
   // next state method as the result arg.
+  int DoThrottle();
+  int DoThrottleComplete();
   int DoNotifyBeforeCreateStream();
   int DoCreateStream();
   int DoCreateStreamComplete(int result);
@@ -394,6 +403,11 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   IPEndPoint remote_endpoint_;
   // Network error details for this transaction.
   NetErrorDetails net_error_details_;
+
+  // Communciate lifetime of transaction to the throttler, and
+  // throttled state to the transaction.
+  std::unique_ptr<NetworkStreamThrottler::Throttle> throttle_;
+
   DISALLOW_COPY_AND_ASSIGN(HttpNetworkTransaction);
 };