cc: Only allow trees created at the current viewport size to draw.

cc/layer_tree_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/layer_tree_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/heads_up_display_layer_impl.h"
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_host_impl.h"
 #include "ui/gfx/vector2d_conversions.h"
 
 namespace cc {
 
 LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
     : layer_tree_host_impl_(layer_tree_host_impl),
       source_frame_number_(-1),
       hud_layer_(0),
       root_scroll_layer_(0),
       currently_scrolling_layer_(0),
       background_color_(0),
       has_transparent_background_(false),
       page_scale_factor_(1),
       page_scale_delta_(1),
       sent_page_scale_delta_(1),
       min_page_scale_factor_(0),
       max_page_scale_factor_(0),
       scrolling_layer_id_from_previous_tree_(0),
       contents_textures_purged_(false),
+      viewport_size_invalid_(false),
       needs_update_draw_properties_(true),
       needs_full_tree_sync_(true) {
 }
 
 LayerTreeImpl::~LayerTreeImpl() {
   // Need to explicitly clear the tree prior to destroying this so that
   // the LayerTreeImpl pointer is still valid in the LayerImpl dtor.
   root_layer_.reset();
 }
 
@@ skipping 57 matching lines @@
   // LayerTreeHost::finishCommitOnImplThread().
   target_tree->set_source_frame_number(source_frame_number());
   target_tree->set_background_color(background_color());
   target_tree->set_has_transparent_background(has_transparent_background());
 
   if (ContentsTexturesPurged())
     target_tree->SetContentsTexturesPurged();
   else
     target_tree->ResetContentsTexturesPurged();
 
+  if (ViewportSizeInvalid())
+    target_tree->SetViewportSizeInvalid();
+  else
+    target_tree->ResetViewportSizeInvalid();
+
   if (hud_layer())
     target_tree->set_hud_layer(static_cast<HeadsUpDisplayLayerImpl*>(
         LayerTreeHostCommon::findLayerInSubtree(
             target_tree->RootLayer(), hud_layer()->id())));
   else
     target_tree->set_hud_layer(NULL);
 }
 
 LayerImpl* LayerTreeImpl::RootScrollLayer() {
   DCHECK(IsActiveTree());
@@ skipping 222 matching lines @@
 void LayerTreeImpl::SetContentsTexturesPurged() {
   contents_textures_purged_ = true;
   layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
 }
 
 void LayerTreeImpl::ResetContentsTexturesPurged() {
   contents_textures_purged_ = false;
   layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
 }
 
+bool LayerTreeImpl::ViewportSizeInvalid() const {
+  return viewport_size_invalid_;
+}
+
+void LayerTreeImpl::SetViewportSizeInvalid() {
+  viewport_size_invalid_ = true;
+  layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
+}
+
+void LayerTreeImpl::ResetViewportSizeInvalid() {
+  viewport_size_invalid_ = false;
+  layer_tree_host_impl_->OnCanDrawStateChangedForTree(this);
+}
+
 Proxy* LayerTreeImpl::proxy() const {
   return layer_tree_host_impl_->proxy();
 }
 
 const LayerTreeSettings& LayerTreeImpl::settings() const {
   return layer_tree_host_impl_->settings();
 }
 
 const RendererCapabilities& LayerTreeImpl::rendererCapabilities() const {
   return layer_tree_host_impl_->rendererCapabilities();
@@ skipping 87 matching lines @@
 
 DebugRectHistory* LayerTreeImpl::debug_rect_history() const {
   return layer_tree_host_impl_->debugRectHistory();
 }
 
 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
   return layer_tree_host_impl_->animationRegistrar();
 }
 
 } // namespace cc