Move purging from OnMemoryState to OnPurgeMemory() in cc/

cc/tiles/gpu_image_decode_cache.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/tiles/gpu_image_decode_cache.h"
 
 #include <inttypes.h>
 
 #include "base/debug/alias.h"
 #include "base/memory/discardable_memory_allocator.h"
@@ skipping 1250 matching lines @@
   return image_data->decode.is_locked();
 }
 
 bool GpuImageDecodeCache::IsInInUseCacheForTesting(
     const DrawImage& image) const {
   auto found = in_use_cache_.find(GenerateInUseCacheKey(image));
   return found != in_use_cache_.end();
 }
 
 void GpuImageDecodeCache::OnMemoryStateChange(base::MemoryState state) {
-  switch (state) {
-    case base::MemoryState::NORMAL:
-      memory_state_ = state;
-      break;
-    case base::MemoryState::THROTTLED:
-    case base::MemoryState::SUSPENDED: {
-      memory_state_ = state;
+  memory_state_ = state;
 
-      // We've just changed our memory state to a (potentially) more
-      // restrictive one. Re-enforce cache limits.
-      base::AutoLock lock(lock_);
-      EnsureCapacity(0);
-      break;
-    }
-    case base::MemoryState::UNKNOWN:
-      // NOT_REACHED.
-      break;
-  }
+  // TODO(bashi): We are going to separate purging from state changes and we
+  // shouldn't purge memory here (crbug.com/684287). Tentatively call
+  // OnPurgeMemory() so that we don't break existing experiments.
+  // (i.e. purge+suspend experiment)
+  if (state == base::MemoryState::SUSPENDED)

[ericrk, 2017/01/30 15:58:56]

The previous logic handled THROTTLED as well, with different limits. Is it
correct to remove that at the moment?

[bashi, 2017/01/31 19:30:56]

The purpose of this CL is to separate purging cache from memory state change
without breaking purge+suspend experiment. Purge+suspend experiment only uses
SUSPENDED state so not handling THROTTLED will be fine.

+    OnPurgeMemory();
+}
+
+void GpuImageDecodeCache::OnPurgeMemory() {
+  base::AutoLock lock(lock_);
+  EnsureCapacity(0);
 }
 
 }  // namespace cc