Make TabLoader a client of memory coordinator

chrome/browser/sessions/tab_loader.h

Index: chrome/browser/sessions/tab_loader.h
diff --git a/chrome/browser/sessions/tab_loader.h b/chrome/browser/sessions/tab_loader.h
index 1ae274c7ef7f742e8bdae3ecffba8c12f726028f..a422931c9f46c624f15cd31704e614964c3e7f47 100644
--- a/chrome/browser/sessions/tab_loader.h
+++ b/chrome/browser/sessions/tab_loader.h
@@ -12,6 +12,7 @@
 #include <set>
 
 #include "base/macros.h"
+#include "base/memory/memory_coordinator_client.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/sessions/session_restore_delegate.h"
@@ -40,7 +41,8 @@ class SessionRestoreStatsCollector;
 // of SessionRestoreImpl doesn't have timing problems.
 class TabLoader : public content::NotificationObserver,
                   public base::RefCounted<TabLoader>,
-                  public TabLoaderCallback {
+                  public TabLoaderCallback,
+                  public base::MemoryCoordinatorClient {
  public:
   using RestoredTab = SessionRestoreDelegate::RestoredTab;
 
@@ -103,14 +105,20 @@ class TabLoader : public content::NotificationObserver,
   // Called when a tab goes away or a load completes.
   void HandleTabClosedOrLoaded(content::NavigationController* controller);
 
-  // Convenience function returning the current memory pressure level.
-  base::MemoryPressureListener::MemoryPressureLevel
-      CurrentMemoryPressureLevel();
+  // Returns true when this is under memory pressure and required to purge
+  // memory by stopping loading tabs.
+  bool ShouldStopLoadingTabs() const;
 
   // React to memory pressure by stopping to load any more tabs.
   void OnMemoryPressure(
       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 
+  // base::MemoryCoordinatorClient implementation:
+  void OnMemoryStateChange(base::MemoryState state) override;
+
+  // Stops loading tabs to purge memory by stopping to load any more tabs.
+  void StopLoadingTabs();
+
   std::unique_ptr<TabLoaderDelegate> delegate_;
 
   // Listens for system under memory pressure notifications and stops loading