CC: Make LayerTreeHostImpl::OnMemoryPressure work for the desktop as well

LayerTreeHostImpl::OnMemoryPressure has only worked for low-end devices.
But it would be good if it works for all devices.

Bug: 839687
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I9f670ab08587ad4c5f626eb74fe5d7c9db256150
Reviewed-on: https://chromium-review.googlesource.com/1107025
Commit-Queue: Gyuyoung Kim <gyuyoung.kim@lge.com>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572216}

cc/trees/layer_tree_host_impl.cc

@@ -2794,18 +2794,14 @@ void LayerTreeHostImpl::ActivateStateForImages() {
 
 void LayerTreeHostImpl::OnMemoryPressure(
     base::MemoryPressureListener::MemoryPressureLevel level) {
-  // Only work for low-end devices for now.
-  if (!base::SysInfo::IsLowEndDevice())
-    return;
-
   switch (level) {
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE:
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
       break;
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
-      ReleaseTileResources();
-      ReleaseTreeResources();
       ClearUIResources();
+      ReleaseTreeResources();
+      ReleaseTileResources();
       if (image_decode_cache_) {
         image_decode_cache_->SetShouldAggressivelyFreeResources(true);
         image_decode_cache_->SetShouldAggressivelyFreeResources(false);