Enable TabManager on Linux

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>
@@ skipping 52 matching lines @@
 using content::BrowserThread;
 using content::WebContents;
 
 namespace memory {
 namespace {
 
 // The default interval in seconds after which to adjust the oom_score_adj
 // value.
 const int kAdjustmentIntervalSeconds = 10;
 
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_CHROMEOS)
 // For each period of this length record a statistic to indicate whether or not
 // the user experienced a low memory event. If this interval is changed,
 // Tabs.Discard.DiscardInLastMinute must be replaced with a new statistic.
 const int kRecentTabDiscardIntervalSeconds = 60;
+#endif
 
 // If there has been no priority adjustment in this interval, assume the
 // machine was suspended and correct the timing statistics.
 const int kSuspendThresholdSeconds = kAdjustmentIntervalSeconds * 4;
 
 // The time during which a tab is protected from discarding after it stops being
 // audible.
 const int kAudioProtectionTimeSeconds = 60;
 
 // Returns a unique ID for a WebContents. Do not cast back to a pointer, as
@@ skipping 103 matching lines @@
   // On Chrome OS, tab manager is always started and tabs can be discarded more
   // than once.
   discard_once_ = false;
 #endif
 
   if (!update_timer_.IsRunning()) {
     update_timer_.Start(FROM_HERE,
                         TimeDelta::FromSeconds(kAdjustmentIntervalSeconds),
                         this, &TabManager::UpdateTimerCallback);
   }
+
+  // MemoryPressureMonitor is not implemented on Linux so far and tabs are never
+  // discarded.
+#if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_CHROMEOS)
   if (!recent_tab_discard_timer_.IsRunning()) {
     recent_tab_discard_timer_.Start(
         FROM_HERE, TimeDelta::FromSeconds(kRecentTabDiscardIntervalSeconds),
         this, &TabManager::RecordRecentTabDiscard);
   }
   start_time_ = NowTicks();
   // Create a |MemoryPressureListener| to listen for memory events.
   base::MemoryPressureMonitor* monitor = base::MemoryPressureMonitor::Get();
   if (monitor) {
     memory_pressure_listener_.reset(new base::MemoryPressureListener(
         base::Bind(&TabManager::OnMemoryPressure, base::Unretained(this))));
     base::MemoryPressureListener::MemoryPressureLevel level =
         monitor->GetCurrentPressureLevel();
     if (level == base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
       OnMemoryPressure(level);
     }
   }
+#endif
 }
 
 void TabManager::Stop() {
   update_timer_.Stop();
   recent_tab_discard_timer_.Stop();
   memory_pressure_listener_.reset();
 }
 
 TabStatsList TabManager::GetTabStats() {
   TabStatsList stats_list(GetUnsortedTabStats());
@@ skipping 613 matching lines @@
     }
   } else {
     // The code here can only be tested under a full browser test.
     AddTabStats(&stats_list);
   }
 
   return stats_list;
 }
 
 }  // namespace memory