Android: Don't destroy LayerTreeHost when Surface goes away

ui/android/resources/ui_resource_provider.cc

Index: ui/android/resources/ui_resource_provider.cc
diff --git a/ui/android/resources/ui_resource_provider.cc b/ui/android/resources/ui_resource_provider.cc
index f9776b890148d7d63f0bcdaa0e886a58e77576c1..66be4a8faaa548e0c31362243f0d0de82c6fcab2 100644
--- a/ui/android/resources/ui_resource_provider.cc
+++ b/ui/android/resources/ui_resource_provider.cc
@@ -10,34 +10,25 @@
 
 namespace ui {
 
-UIResourceProvider::UIResourceProvider()
-    : host_(NULL), supports_etc1_npot_(false) {
+UIResourceProvider::UIResourceProvider(cc::LayerTreeHost* host)
+    : host_(host), supports_etc1_npot_(false) {
 }
 
 UIResourceProvider::~UIResourceProvider() {
-  SetLayerTreeHost(NULL);
+  OnUIResourcesEvicted();
 }
 
-void UIResourceProvider::SetLayerTreeHost(cc::LayerTreeHost* host) {
-  if (host_ == host)
-    return;
-  host_ = host;
-  UIResourcesAreInvalid();
-}
-
-void UIResourceProvider::UIResourcesAreInvalid() {
-  UIResourceClientMap client_map;
-  client_map.swap(ui_resource_client_map_);
+void UIResourceProvider::OnUIResourcesEvicted() {
+  // OnWasEvicted() might cause DeleteUIResource() to get called.
+  UIResourceClientMap client_map(ui_resource_client_map_);
   for (UIResourceClientMap::iterator iter = client_map.begin();
        iter != client_map.end(); iter++) {
-    iter->second->UIResourceIsInvalid();
+    iter->second->OnWasEvicted();
   }
 }
 
 cc::UIResourceId UIResourceProvider::CreateUIResource(
     ui::UIResourceClientAndroid* client) {
-  if (!host_)
-    return 0;
   cc::UIResourceId id = host_->CreateUIResource(client);
   DCHECK(ui_resource_client_map_.find(id) == ui_resource_client_map_.end());
 
@@ -51,9 +42,6 @@ void UIResourceProvider::DeleteUIResource(cc::UIResourceId ui_resource_id) {
   DCHECK(iter != ui_resource_client_map_.end());
 
   ui_resource_client_map_.erase(iter);
-
-  if (!host_)
-    return;
   host_->DeleteUIResource(ui_resource_id);
 }