Make HistoryBackend a client of memory coordinator

components/history/core/browser/history_backend.h

 // 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.
 
 #ifndef COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_
 #define COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 14 matching lines @@
 #include "base/supports_user_data.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "build/build_config.h"
 #include "components/favicon_base/favicon_usage_data.h"
 #include "components/history/core/browser/expire_history_backend.h"
 #include "components/history/core/browser/history_backend_notifier.h"
 #include "components/history/core/browser/history_types.h"
 #include "components/history/core/browser/keyword_id.h"
 #include "components/history/core/browser/thumbnail_database.h"
 #include "components/history/core/browser/visit_tracker.h"
+#include "components/memory_coordinator/common/memory_coordinator_client.h"
 #include "sql/init_status.h"
 
 class HistoryURLProvider;
 struct HistoryURLProviderParams;
 class SkBitmap;
 class TestingProfile;
 struct ThumbnailScore;
 
 namespace base {
 class MessageLoop;
@@ skipping 50 matching lines @@
 // Internal history implementation which does most of the work of the history
 // system. This runs on a background thread (to not block the browser when we
 // do expensive operations) and is NOT threadsafe, so it must only be called
 // from message handlers on the background thread. Invoking on another thread
 // requires threadsafe refcounting.
 //
 // Most functions here are just the implementations of the corresponding
 // functions in the history service. These functions are not documented
 // here, see the history service for behavior.
 class HistoryBackend : public base::RefCountedThreadSafe<HistoryBackend>,
-                       public HistoryBackendNotifier {
+                       public HistoryBackendNotifier,
+                       public memory_coordinator::MemoryCoordinatorClient {
  public:
   // Interface implemented by the owner of the HistoryBackend object. Normally,
   // the history service implements this to send stuff back to the main thread.
   // The unit tests can provide a different implementation if they don't have
   // a history service object.
   class Delegate {
    public:
     virtual ~Delegate() {}
 
     // Called when the database cannot be read correctly for some reason.
@@ skipping 355 matching lines @@
 
   ExpireHistoryBackend* expire_backend() { return &expirer_; }
 #endif
 
   // Returns true if the passed visit time is already expired (used by the sync
   // code to avoid syncing visits that would immediately be expired).
   virtual bool IsExpiredVisitTime(const base::Time& time);
 
   base::Time GetFirstRecordedTimeForTest() { return first_recorded_time_; }
 
+  // memory_coordinator::MemoryCoordinatorClient implementation:
+  void OnMemoryStateChange(memory_coordinator::MemoryState state) override;
+
  protected:
   ~HistoryBackend() override;
 
  private:
   friend class base::RefCountedThreadSafe<HistoryBackend>;
   friend class CommitLaterTask;  // The commit task needs to call Commit().
   friend class HistoryBackendTest;
   friend class HistoryBackendDBBaseTest;  // So the unit tests can poke our
                                           // innards.
   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, DeleteAll);
@@ skipping 81 matching lines @@
   // Returns the name of the Favicons database. This is the new name
   // of the Thumbnails database.
   base::FilePath GetFaviconsFileName() const;
 
   class URLQuerier;
   friend class URLQuerier;
 
   // Does the work of Init.
   void InitImpl(const HistoryDatabaseParams& history_database_params);
 
+  // Asks database to trim memory.
+  void TrimMemory(bool trim_aggressively);
+
   // Called when the system is under memory pressure.
   void OnMemoryPressure(
       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 
   // Closes all databases managed by HistoryBackend. Commits any pending
   // transactions.
   void CloseAllDatabases();
 
   // Adds a single visit to the database, updating the URL information such
   // as visit and typed count. The visit ID of the added visit and the URL ID
@@ skipping 300 matching lines @@
 
   // List of observers
   base::ObserverList<HistoryBackendObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(HistoryBackend);
 };
 
 }  // namespace history
 
 #endif  // COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_H_