plumb network upload into the task manager

chrome/browser/task_manager/sampling/task_group.cc

Index: chrome/browser/task_manager/sampling/task_group.cc
diff --git a/chrome/browser/task_manager/sampling/task_group.cc b/chrome/browser/task_manager/sampling/task_group.cc
index ce8460050d72812df030d2c1fdee2f683bb1718a..cd0c43d84fd0b1b0c488c5a7c49b65897f3efd17 100644
--- a/chrome/browser/task_manager/sampling/task_group.cc
+++ b/chrome/browser/task_manager/sampling/task_group.cc
@@ -91,7 +91,8 @@ TaskGroup::TaskGroup(
       cpu_usage_(0.0),
       gpu_memory_(-1),
       memory_state_(base::MemoryState::UNKNOWN),
-      per_process_network_usage_(-1),
+      per_process_network_usage_rate_(-1),
+      cumulative_per_process_network_usage_(0),
 #if defined(OS_WIN)
       gdi_current_handles_(-1),
       gdi_peak_handles_(-1),
@@ -165,12 +166,13 @@ void TaskGroup::Refresh(const gpu::VideoMemoryUsageStats& gpu_memory_stats,
   const bool network_usage_refresh_enabled =
       TaskManagerObserver::IsResourceRefreshEnabled(REFRESH_TYPE_NETWORK_USAGE,
                                                     refresh_flags);
-  per_process_network_usage_ = network_usage_refresh_enabled ? 0 : -1;
+  per_process_network_usage_rate_ = network_usage_refresh_enabled ? 0 : -1;

[ncarter (slow), 2017/06/14 20:20:59]

Don't you need to zero out cumulative_per_process_network_usage_ here? Otherwise
it'll grow quadratically?

Would be nice to see a task_group_unittest case that catches this (you could
consider moving the test scenarios you already have, from
browser_process_task_unittest.cc to task_group_unittest)

[cburn, 2017/06/16 21:52:27]

We absolutely do, and I will move those tests over and add one to get coverage
on this case. 

   for (Task* task : tasks_) {
     task->Refresh(update_interval, refresh_flags);
-
-    if (network_usage_refresh_enabled && task->ReportsNetworkUsage())
-      per_process_network_usage_ += task->network_usage();
+    if (network_usage_refresh_enabled && task->ReportsNetworkUsage()) {
+      per_process_network_usage_rate_ += task->network_usage_rate();
+      cumulative_per_process_network_usage_ += task->cumulative_network_usage();
+    }
   }
 
   // 2- Refresh GPU memory (if enabled).