Add process start time and CPU time columns to task manager

chrome/browser/task_manager/sampling/task_group.h

Index: chrome/browser/task_manager/sampling/task_group.h
diff --git a/chrome/browser/task_manager/sampling/task_group.h b/chrome/browser/task_manager/sampling/task_group.h
index 8013e72c4e00d2b5ddf2944ef5b3de8115cd54aa..cf3256b1f3cc1a0240f97613c560602d60b5d94e 100644
--- a/chrome/browser/task_manager/sampling/task_group.h
+++ b/chrome/browser/task_manager/sampling/task_group.h
@@ -67,6 +67,8 @@ class TaskGroup {
   bool empty() const { return tasks().empty(); }
 
   double cpu_usage() const { return cpu_usage_; }
+  int64_t start_time() const { return start_time_; }
+  int64_t cpu_time() const { return cpu_time_; }
   int64_t private_bytes() const { return memory_usage_.private_bytes; }
   int64_t shared_bytes() const { return memory_usage_.shared_bytes; }
   int64_t physical_bytes() const { return memory_usage_.physical_bytes; }
@@ -107,6 +109,10 @@ class TaskGroup {
 
   void OnCpuRefreshDone(double cpu_usage);
 
+  void OnStartTimeRefreshDone(int64_t start_time);
+
+  void OnCpuTimeRefreshDone(int64_t cpu_time);
+
   void OnPhysicalMemoryUsageRefreshDone(int64_t physical_bytes);
   void OnMemoryUsageRefreshDone(MemoryUsageStats memory_usage);
 
@@ -143,6 +149,8 @@ class TaskGroup {
 
   // The per process resources usages.
   double cpu_usage_;
+  int64_t start_time_;
+  int64_t cpu_time_;
   MemoryUsageStats memory_usage_;
   int64_t gpu_memory_;
   // The network usage in bytes per second as the sum of all network usages of