base: Make TimeDurationFormat* report failures.

chrome/browser/ui/task_manager/task_manager_table_model.cc

 // Copyright 2015 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 "chrome/browser/ui/task_manager/task_manager_table_model.h"
 
 #include <stddef.h>
 
 #include "base/command_line.h"
 #include "base/i18n/number_formatting.h"
@@ skipping 123 matching lines @@
     if (start_time.is_null())
       return n_a_string_;
 
     return base::TimeFormatShortDateAndTime(start_time);
   }
 
   base::string16 GetCpuTimeText(base::TimeDelta cpu_time) {
     if (cpu_time.is_zero())
       return n_a_string_;
 
-    return base::TimeDurationFormatWithSeconds(cpu_time,
-                                               base::DURATION_WIDTH_NARROW);
+    base::string16 str;
+    if (!base::TimeDurationFormatWithSeconds(
+            cpu_time, base::DURATION_WIDTH_NARROW, &str)) {
+      LOG(ERROR) << "Failed to format duration " << cpu_time.ToInternalValue();

[ncarter (slow), 2017/03/06 21:52:37]

Since we have a n/a string here, I think we gracefully handle the error already
(I don't know what else we could do to handle such an error). I'd probably omit
the LOG(ERROR) altogether.

[Daniel Erat, 2017/03/06 22:47:10]

i don't think these failures should ever occur, so this may be useful in
tracking down the cause if you start getting reports of unexpected n/a strings
(see the linked bug about bad battery-time-to-empty strings). i'll remove the
logging if you'd prefer that, though.

[ncarter (slow), 2017/03/06 23:04:52]

Let's omit the LOG(ERROR); I don't think it's worth the binary-size cost [those
get compiled into release right?].

[Daniel Erat, 2017/03/06 23:19:34]

done (although i've more than offset that binary-size reduction by adding more
temporary logging to TimeDurationFormat, where i think we're currently seeing a
problem) :-P

+      return n_a_string_;
+    }
+    return str;
   }
 
   base::string16 GetMemoryUsageText(int64_t memory_usage, bool has_duplicates) {
     if (memory_usage == -1)
       return n_a_string_;
 
 #if defined(OS_MACOSX)
     // System expectation is to show "100 kB", "200 MB", etc.
     // TODO(thakis): [This TODO has been taken as is from the old task manager]:
     // Switch to metric units (as opposed to powers of two).
@@ skipping 773 matching lines @@
 
 bool TaskManagerTableModel::IsTaskFirstInGroup(int row_index) const {
   if (row_index == 0)
     return true;
 
   return observed_task_manager()->GetProcessId(tasks_[row_index - 1]) !=
       observed_task_manager()->GetProcessId(tasks_[row_index]);
 }
 
 }  // namespace task_manager