Make HistoryBackend a client of memory coordinator

content/browser/browser_main_loop.h

Index: content/browser/browser_main_loop.h
diff --git a/content/browser/browser_main_loop.h b/content/browser/browser_main_loop.h
index c126956709e46ef613fedb162e0ccf82a39e1cd9..e8e3eabefe2d5d796023718eb11b7298cf62f304 100644
--- a/content/browser/browser_main_loop.h
+++ b/content/browser/browser_main_loop.h
@@ -50,10 +50,6 @@ class MidiManager;
 }  // namespace midi
 }  // namespace media
 
-namespace memory_coordinator {
-class MemoryCoordinator;
-}  // namespace memory_coordinator
-
 namespace mojo {
 namespace edk {
 class ScopedIPCSupport;
@@ -148,10 +144,6 @@ class CONTENT_EXPORT BrowserMainLoop {
 
   void StopStartupTracingTimer();
 
-  memory_coordinator::MemoryCoordinator* memory_coordinator() const {
-    return memory_coordinator_.get();
-  }
-
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   media::DeviceMonitorMac* device_monitor_mac() const {
     return device_monitor_mac_.get();
@@ -259,7 +251,6 @@ class CONTENT_EXPORT BrowserMainLoop {
   // Members initialized in |PreCreateThreads()| -------------------------------
   // Torn down in ShutdownThreadsAndCleanUp.
   std::unique_ptr<base::MemoryPressureMonitor> memory_pressure_monitor_;
-  std::unique_ptr<memory_coordinator::MemoryCoordinator> memory_coordinator_;
 
   // Members initialized in |CreateThreads()| ----------------------------------
   std::unique_ptr<BrowserProcessSubThread> db_thread_;