[cc] Evict UIResources when the renderer is not visible

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
@@ skipping 183 matching lines @@
       last_sent_memory_visible_and_nearby_bytes_(0),
       last_sent_memory_use_bytes_(0),
       zero_budget_(false),
       device_scale_factor_(1.f),
       overhang_ui_resource_id_(0),
       overdraw_bottom_height_(0.f),
       device_viewport_valid_for_tile_management_(true),
       external_stencil_test_enabled_(false),
       animation_registrar_(AnimationRegistrar::Create()),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
-      need_to_update_visible_tiles_before_draw_(false) {
+      need_to_update_visible_tiles_before_draw_(false),
+      ui_resource_eviction_count_(0) {
   DCHECK(proxy_->IsImplThread());
   DidVisibilityChange(this, visible_);
 
   SetDebugState(settings.initial_debug_state);
 
   if (settings.calculate_top_controls_position) {
     top_controls_manager_ =
         TopControlsManager::Create(this,
                                    settings.top_controls_height,
                                    settings.top_controls_show_threshold,
@@ skipping 89 matching lines @@
         "cc", "LayerTreeHostImpl::CanDraw viewport size recently changed",
         TRACE_EVENT_SCOPE_THREAD);
     return false;
   }
   if (active_tree_->ContentsTexturesPurged()) {
     TRACE_EVENT_INSTANT0(
         "cc", "LayerTreeHostImpl::CanDraw contents textures purged",
         TRACE_EVENT_SCOPE_THREAD);
     return false;
   }
+  if (active_tree_->ui_resource_eviction_count_recreated() !=
+      ui_resource_eviction_count()) {
+    TRACE_EVENT_INSTANT0(
+        "cc", "LayerTreeHostImpl::CanDraw UI resources evicted not recreated",
+        TRACE_EVENT_SCOPE_THREAD);
+    return false;
+  }
   return true;
 }
 
 void LayerTreeHostImpl::Animate(base::TimeTicks monotonic_time,
                                 base::Time wall_clock_time) {
   if (input_handler_client_)
     input_handler_client_->Animate(monotonic_time);
   AnimatePageScale(monotonic_time);
   AnimateLayers(monotonic_time, wall_clock_time);
   AnimateScrollbars(monotonic_time);
@@ skipping 1227 matching lines @@
 
 void LayerTreeHostImpl::SetVisible(bool visible) {
   DCHECK(proxy_->IsImplThread());
 
   if (visible_ == visible)
     return;
   visible_ = visible;
   DidVisibilityChange(this, visible_);
   EnforceManagedMemoryPolicy(ActualManagedMemoryPolicy());
 
+  if (!visible_)
+    DeleteAllUIResources();
+
   // Evict tiles immediately if invisible since this tab may never get another
   // draw or timer tick.
   if (!visible_)
     ManageTiles();
 
   if (!renderer_)
     return;
 
   renderer_->SetVisible(visible);
 }
@@ skipping 1061 matching lines @@
 
 void LayerTreeHostImpl::DeleteUIResource(UIResourceId uid) {
   ResourceProvider::ResourceId id = ResourceIdForUIResource(uid);
   if (id) {
     resource_provider_->DeleteResource(id);
     ui_resource_map_.erase(uid);
   }
 }
 
 void LayerTreeHostImpl::DeleteAllUIResources() {
+  if (ui_resource_map_.empty())
+    return;
+
   for (UIResourceMap::const_iterator iter = ui_resource_map_.begin();
       iter != ui_resource_map_.end();
       ++iter) {
     resource_provider_->DeleteResource(iter->second);
   }
   ui_resource_map_.clear();
+
+  ui_resource_eviction_count_ += 1;
+  client_->SetNeedsCommitOnImplThread();
+  client_->OnCanDrawStateChanged(CanDraw());
+  client_->RenewTreePriority();

[powei, 2013/09/09 20:34:25]

Maybe a stupid question, but what's the purpose of calling this method?  Is
there an implicit contract that says priority should be updated when CanDraw
changes?

[ccameron, 2013/09/09 21:01:16]

Oops! I needed to update RenewTreePriority to "prefer new content" when this
happens... that way we'll switch to the new tree (with all its UI resources).
Without that change, this did nothing...

 }
 
 ResourceProvider::ResourceId LayerTreeHostImpl::ResourceIdForUIResource(
     UIResourceId uid) const {
   UIResourceMap::const_iterator iter = ui_resource_map_.find(uid);
   if (iter != ui_resource_map_.end())
     return iter->second;
   return 0;
 }
 
 }  // namespace cc