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 198f1ce61ffe492414af43e9a4e608c3a788050f..aa49723c23c177834533405196b411582316e764 100644
--- a/net/http/http_network_transaction.h
+++ b/net/http/http_network_transaction.h
@@ -17,6 +17,7 @@
 #include "crypto/ec_private_key.h"
 #include "net/base/net_error_details.h"
 #include "net/base/net_export.h"
+#include "net/base/network_throttle_manager.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 NetworkThrottleManager::ThrottleDelegate {
  public:
   HttpNetworkTransaction(RequestPriority priority,
                          HttpNetworkSession* session);
@@ -121,6 +123,9 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   void OnQuicBroken() override;
   void GetConnectionAttempts(ConnectionAttempts* out) const override;
 
+  // NetworkThrottleManager::Delegate methods:
+  void OnThrottleStateChanged() override;
+
  private:
   friend class HttpNetworkTransactionSSLTest;
 
@@ -142,6 +147,8 @@ 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,
@@ -188,6 +195,8 @@ 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);
@@ -383,6 +392,11 @@ class NET_EXPORT_PRIVATE HttpNetworkTransaction
   IPEndPoint remote_endpoint_;
   // Network error details for this transaction.
   NetErrorDetails net_error_details_;
+
+  // Communicate lifetime of transaction to the throttler, and
+  // throttled state to the transaction.
+  std::unique_ptr<NetworkThrottleManager::Throttle> throttle_;
+
   DISALLOW_COPY_AND_ASSIGN(HttpNetworkTransaction);
 };