memory coordinator: Add MemoryCoordinatorClient::OnPurgeMemory()

cc/raster/staging_buffer_pool.cc

 // Copyright 2016 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 "cc/raster/staging_buffer_pool.h"
 
 #include <memory>
 
 #include "base/memory/memory_coordinator_client_registry.h"
 #include "base/memory/ptr_util.h"
@@ skipping 414 matching lines @@
       if (busy_buffers_.front()->last_usage > time)
         return;
 
       busy_buffers_.front()->DestroyGLResources(gl);
       RemoveStagingBuffer(busy_buffers_.front().get());
       busy_buffers_.pop_front();
     }
   }
 }
 
-void StagingBufferPool::OnMemoryStateChange(base::MemoryState state) {
-  switch (state) {
-    case base::MemoryState::NORMAL:
-      // TODO(tasak): go back to normal state.
-      break;
-    case base::MemoryState::THROTTLED:
-      // TODO(tasak): make the limits of this component's caches smaller to
-      // save memory usage.
-      break;
-    case base::MemoryState::SUSPENDED: {
-      base::AutoLock lock(lock_);
-      // Release all buffers, regardless of how recently they were used.
-      ReleaseBuffersNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
-    } break;
-    case base::MemoryState::UNKNOWN:
-      // NOT_REACHED.
-      break;
-  }
+void StagingBufferPool::OnPurgeMemory() {
+  base::AutoLock lock(lock_);
+  // Release all buffers, regardless of how recently they were used.
+  ReleaseBuffersNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
 }
 
 }  // namespace cc