Enable TabManager on Linux

chrome/browser/memory/tab_manager.cc

Index: chrome/browser/memory/tab_manager.cc
diff --git a/chrome/browser/memory/tab_manager.cc b/chrome/browser/memory/tab_manager.cc
index a2299862de6deec44a10eb2a4db511c985a7d215..1c64eccf2d91db2943a0410efeec80ab74d86b40 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -70,10 +70,12 @@ namespace {
 // 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.
@@ -197,6 +199,10 @@ void TabManager::Start() {
                         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),
@@ -214,6 +220,7 @@ void TabManager::Start() {
       OnMemoryPressure(level);
     }
   }
+#endif
 }
 
 void TabManager::Stop() {