Fix the views Task Manager on Mac showing 0s for the Shared Memory

chrome/browser/task_management/sampling/task_group_sampler.cc

Index: chrome/browser/task_management/sampling/task_group_sampler.cc
diff --git a/chrome/browser/task_management/sampling/task_group_sampler.cc b/chrome/browser/task_management/sampling/task_group_sampler.cc
index 93b0c2e0bd1e2cde67cc0d789b4b653182604961..f3ded8a27e5242c081587a24588e599e9cddc352 100644
--- a/chrome/browser/task_management/sampling/task_group_sampler.cc
+++ b/chrome/browser/task_management/sampling/task_group_sampler.cc
@@ -122,10 +122,13 @@ double TaskGroupSampler::RefreshCpuUsage() {
 MemoryUsageStats TaskGroupSampler::RefreshMemoryUsage() {
   DCHECK(worker_pool_sequenced_checker_.CalledOnValidSequencedThread());
 
-  // TODO(afakhry): Integrate Bruce's CL for faster retrieval of physical memory
-  // on Windows here.

[ncarter (slow), 2016/05/19 22:30:36]

Did we ever do this?

[afakhry, 2016/05/20 00:34:35]

We haven't. One reason was that Bruce's approach doesn't match our
task/group/group sampler architecture.

I wanted to discuss this with you, actually. I think it's not worth it adding
ugliness and code complexity to our design, from which the return is not big.
Our design is already fast and running in a background thread. WDT? I can leave
that TODO if you want.

-
   MemoryUsageStats memory_usage;
+#if defined(OS_MACOSX)
+  if (process_metrics_->GetMemoryBytes(&memory_usage.private_bytes,
+                                       &memory_usage.shared_bytes)) {
+    memory_usage.physical_bytes = memory_usage.private_bytes;
+  }
+#else
   // Refreshing the physical/private/shared memory at one shot.
   base::WorkingSetKBytes ws_usage;
   if (process_metrics_->GetWorkingSetKBytes(&ws_usage)) {
@@ -144,11 +147,13 @@ MemoryUsageStats TaskGroupSampler::RefreshMemoryUsage() {
         static_cast<int64_t>(process_metrics_->GetWorkingSetSize());
     memory_usage.physical_bytes -=
         static_cast<int64_t>(ws_usage.shareable * 1024);
-#endif
+#endif  // defined(OS_LINUX)
+
 #if defined(OS_CHROMEOS)
     memory_usage.swapped_bytes = ws_usage.swapped * 1024;
-#endif
+#endif  // defined(OS_CHROMEOS)
   }
+#endif  // defined(OS_MACOSX)
 
   return memory_usage;
 }