Split JobController count histograms into three separate histograms:

net/http/http_stream_factory_impl.cc

 // Copyright (c) 2012 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 "net/http/http_stream_factory_impl.h"
 
 #include <string>
 #include <tuple>
 
 #include "base/logging.h"
@@ skipping 354 matching lines @@
       job_controller_set_.size() <= last_logged_job_controller_count_) {
     return;
   }
   last_logged_job_controller_count_ = job_controller_set_.size();
 
   UMA_HISTOGRAM_COUNTS_1M("Net.JobControllerSet.CountOfJobController",
                           job_controller_set_.size());
 
   int alt_job_count = 0;
   int main_job_count = 0;
-  int pending_request_count = 0;
-  int preconnect_controller_count = 0;
+  size_t pending_request_count = 0;

[xunjieli, 2017/04/19 15:12:13]

nit: s/pending_request_count/num_controllers_with_request

[Zhongyi Shi, 2017/04/19 17:38:53]

Done.

+  size_t preconnect_controller_count = 0;

[xunjieli, 2017/04/19 15:12:13]

nit: s/preconnect_controller_count/num_controllers_for_preconnect

[Zhongyi Shi, 2017/04/19 17:38:53]

Done.

   for (const auto& job_controller : job_controller_set_) {
     DCHECK(job_controller->HasPendingAltJob() ||
            job_controller->HasPendingMainJob());
     // Additionally logs the states of the jobs if there are at least 500
     // controllers, which suggests that there might be a leak.
     if (job_controller_set_.size() >= 500)
       job_controller->LogHistograms();
     // For a preconnect controller, it should have exactly the main job.
     if (job_controller->is_preconnect()) {
       preconnect_controller_count++;
       continue;
     }
     // For non-preconnects.
     if (job_controller->HasPendingRequest())
       pending_request_count++;
     if (job_controller->HasPendingAltJob())
       alt_job_count++;
     if (job_controller->HasPendingMainJob())
       main_job_count++;
   }
-  UMA_HISTOGRAM_COUNTS_1M("Net.JobControllerSet.CountOfPreconnect",
-                          preconnect_controller_count);
+  UMA_HISTOGRAM_COUNTS_1M(
+      "Net.JobControllerSet.CountOfJobController.Preconnect",
+      preconnect_controller_count);
+  UMA_HISTOGRAM_COUNTS_1M(
+      "Net.JobControllerSet.CountOfJobCOntroller.NonPerconnect.PendingRequest",

[xunjieli, 2017/04/19 15:12:14]

s/COntroller/Controller
s/Perconnect/Preconnect

[Zhongyi Shi, 2017/04/19 17:38:53]

Done.

+      pending_request_count);
+
+  DCHECK_GE(job_controller_set_.size() - preconnect_controller_count,
+            pending_request_count);

[xunjieli, 2017/04/19 15:12:13]

nit: can we calculate this value and DCHECK on it?
DCHECK_GE(num_controllers_with_no_request, 0);

UMA_HISTOGRAM...(... num_controllers_with_no_request);

[Zhongyi Shi, 2017/04/19 17:38:53]

DCHECK_GE(job_controller_set_.size() - preconnect_controller_count,          
pending_request_count) does the DCHECK and prevents overflow. 

[xunjieli, 2017/04/19 17:50:04]

We can't depend on DCHECK doing the overflow check since we won't have it in
release build.

I think it's fine to assume there is no overflow because in one iteration, we
either increment num_controllers_with_request or num_controllers_for_preconnect
and not both.

So |job_controller_set_.size()| should be greater or equal to sum of
num_controllers_with_request and num_controller_for_preconnect.

I think we should get rid of the DCHECK. 

+  UMA_HISTOGRAM_COUNTS_1M(
+      "Net.JobControllerSet.CountOfJobController.NonPreconnect.RequestGone",
+      job_controller_set_.size() - preconnect_controller_count -
+          pending_request_count);
+
   UMA_HISTOGRAM_COUNTS_1M("Net.JobControllerSet.CountOfNonPreconnectAltJob",
                           alt_job_count);
   UMA_HISTOGRAM_COUNTS_1M("Net.JobControllerSet.CountOfNonPreconnectMainJob",
                           main_job_count);
-  UMA_HISTOGRAM_COUNTS_1M("Net.JobControllerSet.CountOfPendingRequest",
-                          pending_request_count);
 }
 
 void HttpStreamFactoryImpl::DumpMemoryStats(
     base::trace_event::ProcessMemoryDump* pmd,
     const std::string& parent_absolute_name) const {
   if (job_controller_set_.empty())
     return;
   std::string name =
       base::StringPrintf("%s/stream_factory", parent_absolute_name.c_str());
   base::trace_event::MemoryAllocatorDump* factory_dump =
@@ skipping 29 matching lines @@
   factory_dump->AddScalar("main_job_count",
                           base::trace_event::MemoryAllocatorDump::kUnitsObjects,
                           main_job_count);
   // The number of preconnect controllers.
   factory_dump->AddScalar("preconnect_count",
                           base::trace_event::MemoryAllocatorDump::kUnitsObjects,
                           preconnect_controller_count);
 }
 
 }  // namespace net