Add histograms for network activity, and total/cumulative

net/http/http_cache_transaction.cc

Index: net/http/http_cache_transaction.cc
===================================================================
--- net/http/http_cache_transaction.cc	(revision 150909)
+++ net/http/http_cache_transaction.cc	(working copy)
@@ -745,12 +745,15 @@
   if (rv != OK)
     return rv;
 
+  ReportNetworkActionStart();
   next_state_ = STATE_SEND_REQUEST_COMPLETE;
   rv = network_trans_->Start(request_, io_callback_, net_log_);
   return rv;
 }
 
 int HttpCache::Transaction::DoSendRequestComplete(int result) {
+  ReportNetworkActionFinish();
+
   if (!cache_)
     return ERR_UNEXPECTED;
 
@@ -839,6 +842,7 @@
 }
 
 int HttpCache::Transaction::DoNetworkRead() {
+  ReportNetworkActionStart();
   next_state_ = STATE_NETWORK_READ_COMPLETE;
   return network_trans_->Read(read_buf_, io_buf_len_, io_callback_);
 }
@@ -846,6 +850,8 @@
 int HttpCache::Transaction::DoNetworkReadComplete(int result) {
   DCHECK(mode_ & WRITE || mode_ == NONE);
 
+  ReportNetworkActionFinish();
+
   if (!cache_)
     return ERR_UNEXPECTED;
 
@@ -1773,6 +1779,7 @@
   DCHECK(network_trans_.get());
   DCHECK_EQ(STATE_NONE, next_state_);
 
+  ReportNetworkActionStart();
   next_state_ = STATE_SEND_REQUEST_COMPLETE;
   int rv = network_trans_->RestartIgnoringLastError(io_callback_);
   if (rv != ERR_IO_PENDING)
@@ -1786,6 +1793,7 @@
   DCHECK(network_trans_.get());
   DCHECK_EQ(STATE_NONE, next_state_);
 
+  ReportNetworkActionStart();
   next_state_ = STATE_SEND_REQUEST_COMPLETE;
   int rv = network_trans_->RestartWithCertificate(client_cert, io_callback_);
   if (rv != ERR_IO_PENDING)
@@ -1799,6 +1807,7 @@
   DCHECK(network_trans_.get());
   DCHECK_EQ(STATE_NONE, next_state_);
 
+  ReportNetworkActionStart();
   next_state_ = STATE_SEND_REQUEST_COMPLETE;
   int rv = network_trans_->RestartWithAuth(credentials, io_callback_);
   if (rv != ERR_IO_PENDING)
@@ -2232,6 +2241,16 @@
     transaction_delegate_->OnCacheActionFinish();
 }
 
+void HttpCache::Transaction::ReportNetworkActionStart() {
+  if (transaction_delegate_)
+    transaction_delegate_->OnNetworkActionStart();
+}
+
+void HttpCache::Transaction::ReportNetworkActionFinish() {
+  if (transaction_delegate_)
+    transaction_delegate_->OnNetworkActionFinish();
+}
+
 void HttpCache::Transaction::UpdateTransactionPattern(
     TransactionPattern new_transaction_pattern) {
   if (transaction_pattern_ == PATTERN_NOT_COVERED)