[Tentaive patch for discussion] Add Purge+Suspend metrics as UMA.

chrome/browser/memory/tab_manager.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 "chrome/browser/memory/tab_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/observer_list.h"
 #include "base/process/process.h"
+#include "base/process/process_metrics.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/tick_clock.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/media/webrtc/media_capture_devices_dispatcher.h"
@@ skipping 630 matching lines @@
 
 #if defined(OS_CHROMEOS)
   TabStatsList stats_list = GetTabStats();
   // This starts the CrOS specific OOM adjustments in /proc/<pid>/oom_score_adj.
   delegate_->AdjustOomPriorities(stats_list);
 #endif
 
   PurgeAndSuspendBackgroundedTabs();
 }
 
+bool TabManager::CanPurgeAndSuspendBackgroundedTab(
+    int64_t target_web_contents_id) const {
+  TabStripModel* model;
+  int idx = FindTabStripModelById(target_web_contents_id, &model);
+
+  if (idx == -1)
+    return false;
+
+  WebContents* web_contents = model->GetWebContentsAt(idx);
+
+  // Do not suspend tabs that are playing either playing audio or accessing the
+  // microphone or camera as it's too distruptive to the user experience.
+  if (IsMediaTab(web_contents))
+    return false;
+
+  if (web_contents->GetContentsMimeType() == "application/pdf")
+    return false;
+
+  // Do not purge and suspend a tab that was explicitly disallowed to.
+  // Note: reused tab discarding logic.
+  if (!IsTabAutoDiscardable(web_contents))
+    return false;
+
+  return true;
+}
+
+void TabManager::RecordPurgeAndSuspendMetrics(
+    const base::ProcessHandle& handle) {
+  std::unique_ptr<base::ProcessMetrics> process_metrics(
+      base::ProcessMetrics::CreateProcessMetrics(handle));
+  size_t private_bytes, shared_bytes;
+  if (process_metrics->GetMemoryBytes(&private_bytes, &shared_bytes)) {
+    UMA_HISTOGRAM_MEMORY_KB("Memory.PurgeAndSuspend.PrivateBytesKB",
+                            private_bytes);
+    UMA_HISTOGRAM_MEMORY_KB("Memory.PurgeAndSuspend.SharedBytesKB",
+                            shared_bytes);
+  }
+}
+
 void TabManager::PurgeAndSuspendBackgroundedTabs() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   if (!command_line.HasSwitch(switches::kPurgeAndSuspendTime))
     return;
   int purge_and_suspend_time = 0;
   if (!base::StringToInt(
           command_line.GetSwitchValueASCII(switches::kPurgeAndSuspendTime),
           &purge_and_suspend_time)) {
     return;
   }
   if (purge_and_suspend_time <= 0)
     return;
   auto purge_and_suspend_time_threshold =
       NowTicks() - base::TimeDelta::FromSeconds(purge_and_suspend_time);
   auto tab_stats = GetUnsortedTabStats();
   for (auto& tab : tab_stats) {
     if (!tab.render_process_host->IsProcessBackgrounded())
       continue;
     // TODO(hajimehoshi): Now calling PurgeAndSuspend is implemented without
     // timers for simplicity, so PurgeAndSuspend is called even after the
     // renderer is purged and suspended once. This should be replaced with
     // timers if we want necessary and sufficient signals.
     if (tab.last_active > purge_and_suspend_time_threshold)
       continue;
-    tab.render_process_host->PurgeAndSuspend();
+
+    if (CanPurgeAndSuspendBackgroundedTab(tab.tab_contents_id))
+      continue;
+
+    if (tab.render_process_host->GetLastPurgeAndSuspendTime() <
+        tab.last_active) {
+      // If purge_and_suspend is disabled, PurgeAndSuspend() just updates
+      // LastPurgeAndSuspendTime. So we can avoid invoking
+      // RecordPurgeAndSuspendMetrics twice.
+      tab.render_process_host->PurgeAndSuspend();
+
+      if (!task_runner_.get())
+        task_runner_ = base::ThreadTaskRunnerHandle::Get();
+      task_runner_->PostDelayedTask(
+          FROM_HERE,
+          base::Bind(&TabManager::RecordPurgeAndSuspendMetrics,
+                     base::Unretained(this),
+                     base::ConstRef(tab.render_process_host->GetHandle())),
+          base::TimeDelta::FromSeconds(15));
+    }
   }
 }
 
 WebContents* TabManager::DiscardWebContentsAt(int index, TabStripModel* model) {
   // Can't discard active index.
   if (model->active_index() == index)
     return nullptr;
 
   WebContents* old_contents = model->GetWebContentsAt(index);
 
@@ skipping 231 matching lines @@
   // platform.
   std::string allow_multiple_discards = variations::GetVariationParamValue(
       features::kAutomaticTabDiscarding.name, "AllowMultipleDiscards");
   return (allow_multiple_discards != "true");
 #else
   return false;
 #endif
 }
 
 }  // namespace memory