Reenable release check for LayerTreeHost destruction in main frame.

Bug: 895883
Change-Id: I377cc6aaf8c9231a81eb100a720e83fa04b9d9a7
Reviewed-on: https://chromium-review.googlesource.com/c/1318570
Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605499}

cc/trees/layer_tree_host.cc

@@ -180,8 +180,8 @@ void LayerTreeHost::InitializeProxy(std::unique_ptr<Proxy> proxy) {
 
 LayerTreeHost::~LayerTreeHost() {
   // Track when we're inside a main frame to see if compositor is being
-  // destroyed midway which causes a crash. crbug.com/654672
-  DCHECK(!inside_main_frame_);
+  // destroyed midway which causes a crash. crbug.com/895883
+  CHECK(!inside_main_frame_);
   TRACE_EVENT0("cc", "LayerTreeHost::~LayerTreeHost");
 
   // Clear any references into the LayerTreeHost.