UI resource are evicted when LTH is set to 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 182 matching lines @@
       max_memory_needed_bytes_(0),
       last_sent_memory_visible_bytes_(0),
       last_sent_memory_visible_and_nearby_bytes_(0),
       last_sent_memory_use_bytes_(0),
       zero_budget_(false),
       device_scale_factor_(1.f),
       overdraw_bottom_height_(0.f),
       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_resources_evicted_(false) {
   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 84 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 (ui_resources_evicted_) {
+    TRACE_EVENT_INSTANT0(
+        "cc", "LayerTreeHostImpl::CanDraw ui resources evicted",
+        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 1211 matching lines @@
 
 void LayerTreeHostImpl::SetVisible(bool visible) {
   DCHECK(proxy_->IsImplThread());
 
   if (visible_ == visible)
     return;
   visible_ = visible;
   DidVisibilityChange(this, visible_);
   EnforceManagedMemoryPolicy(ActualManagedMemoryPolicy());
 
-  // Evict tiles immediately if invisible since this tab may never get another
-  // draw or timer tick.
-  if (!visible_)
+  if (!visible_) {
+    // Evict tiles immediately if invisible since this tab may never get another
+    // draw or timer tick.
     ManageTiles();
 
+    // Evict UI resources
+    ui_resources_evicted_ = ui_resource_map_.size() > 0;
+    ReleaseUIResources();
+  }
+
   if (!renderer_)
     return;
 
   renderer_->SetVisible(visible);
 }
 
 ManagedMemoryPolicy LayerTreeHostImpl::ActualManagedMemoryPolicy() const {
   ManagedMemoryPolicy actual = cached_managed_memory_policy_;
   if (debug_state_.rasterize_only_visible_content) {
     actual.priority_cutoff_when_not_visible =
@@ skipping 15 matching lines @@
 }
 
 void LayerTreeHostImpl::ReleaseTreeResources() {
   if (active_tree_->root_layer())
     SendReleaseResourcesRecursive(active_tree_->root_layer());
   if (pending_tree_ && pending_tree_->root_layer())
     SendReleaseResourcesRecursive(pending_tree_->root_layer());
   if (recycle_tree_ && recycle_tree_->root_layer())
     SendReleaseResourcesRecursive(recycle_tree_->root_layer());
 
-  // Remove all existing maps from UIResourceId to ResourceId.
-  ui_resource_map_.clear();
+  ReleaseUIResources();
 }
 
 void LayerTreeHostImpl::CreateAndSetRenderer(
     OutputSurface* output_surface,
     ResourceProvider* resource_provider,
     bool skip_gl_renderer) {
   DCHECK(!renderer_);
   if (output_surface->capabilities().delegated_rendering) {
     renderer_ =
         DelegatingRenderer::Create(this, output_surface, resource_provider);
@@ skipping 932 matching lines @@
       bitmap->GetSize(),
       resource_provider_->best_texture_format(),
       ResourceProvider::TextureUsageAny);
 
   ui_resource_map_[uid] = id;
   resource_provider_->SetPixels(id,
                                 reinterpret_cast<uint8_t*>(bitmap->GetPixels()),
                                 gfx::Rect(bitmap->GetSize()),
                                 gfx::Rect(bitmap->GetSize()),
                                 gfx::Vector2d(0, 0));
+
+  // Once any UI resource creation has been completed, we can assume that the
+  // evicted UI resources will have been recovered by the time CanDraw is
+  // checked.
+  ui_resources_evicted_ = false;
 }
 
 void LayerTreeHostImpl::DeleteUIResource(UIResourceId uid) {
   ResourceProvider::ResourceId id = ResourceIdForUIResource(uid);
   if (id) {
     resource_provider_->DeleteResource(id);
     ui_resource_map_.erase(uid);
   }
 }
 
 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;
 }
 
+void LayerTreeHostImpl::ReleaseUIResources() {
+  for (UIResourceMap::const_iterator iter = ui_resource_map_.begin();
+      iter != ui_resource_map_.end();
+      ++iter) {
+    resource_provider_->DeleteResource(iter->second);
+  }
+  ui_resource_map_.clear();
+}
+
 }  // namespace cc