Move viewport scrolling logic into separate class

cc/trees/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/trees/layer_tree_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/animation/keyframed_animation_curve.h"
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/animation/scrollbar_animation_controller_linear_fade.h"
 #include "cc/animation/scrollbar_animation_controller_thinning.h"
 #include "cc/base/math_util.h"
 #include "cc/base/synced_property.h"
 #include "cc/base/util.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/input/page_scale_animation.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/render_surface_impl.h"
 #include "cc/layers/scrollbar_layer_impl_base.h"
+#include "cc/layers/viewport.h"
 #include "cc/resources/ui_resource_request.h"
 #include "cc/trees/layer_tree_host_common.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/occlusion_tracker.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 
 namespace cc {
 
@@ skipping 60 matching lines @@
       contents_textures_purged_(false),
       viewport_size_invalid_(false),
       needs_update_draw_properties_(true),
       needs_full_tree_sync_(true),
       next_activation_forces_redraw_(false),
       has_ever_been_drawn_(false),
       render_surface_layer_list_id_(0),
       top_controls_shrink_blink_size_(false),
       top_controls_height_(0),
       top_controls_shown_ratio_(top_controls_shown_ratio) {
+  viewport_ = Viewport::Create(layer_tree_host_impl);
 }
 
 LayerTreeImpl::~LayerTreeImpl() {
   BreakSwapPromises(SwapPromise::SWAP_FAILS);
 
   // Need to explicitly clear the tree prior to destroying this so that
   // the LayerTreeImpl pointer is still valid in the LayerImpl dtor.
   DCHECK(!root_layer_);
   DCHECK(layers_with_copy_output_request_.empty());
 }
@@ skipping 23 matching lines @@
   if (outer_viewport_scroll_layer_)
     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
   inner_viewport_scroll_delegate_proxy_ = nullptr;
   outer_viewport_scroll_delegate_proxy_ = nullptr;
 
   root_layer_ = layer.Pass();
   currently_scrolling_layer_ = NULL;
   inner_viewport_scroll_layer_ = NULL;
   outer_viewport_scroll_layer_ = NULL;
   page_scale_layer_ = NULL;
+  viewport_->SetViewportLayers(inner_viewport_scroll_layer_,
+                               outer_viewport_scroll_layer_);
 
   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 }
 
 LayerImpl* LayerTreeImpl::InnerViewportScrollLayer() const {
   return inner_viewport_scroll_layer_;
 }
 
 LayerImpl* LayerTreeImpl::OuterViewportScrollLayer() const {
   return outer_viewport_scroll_layer_;
@@ skipping 30 matching lines @@
   if (inner_viewport_scroll_layer_)
     inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
   if (outer_viewport_scroll_layer_)
     outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
   inner_viewport_scroll_delegate_proxy_ = nullptr;
   outer_viewport_scroll_delegate_proxy_ = nullptr;
   inner_viewport_scroll_layer_ = NULL;
   outer_viewport_scroll_layer_ = NULL;
   page_scale_layer_ = NULL;
   currently_scrolling_layer_ = NULL;
+  viewport_->SetViewportLayers(inner_viewport_scroll_layer_,
+                               outer_viewport_scroll_layer_);
 
   render_surface_layer_list_.clear();
   set_needs_update_draw_properties();
   return root_layer_.Pass();
 }
 
 void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   // The request queue should have been processed and does not require a push.
   DCHECK_EQ(ui_resource_request_queue_.size(), 0u);
 
@@ skipping 295 matching lines @@
   DCHECK(page_scale_layer_);
 
   inner_viewport_scroll_layer_ =
       LayerById(inner_viewport_scroll_layer_id);
   DCHECK(inner_viewport_scroll_layer_);
 
   outer_viewport_scroll_layer_ =
       LayerById(outer_viewport_scroll_layer_id);
   DCHECK(outer_viewport_scroll_layer_ ||
          outer_viewport_scroll_layer_id == Layer::INVALID_ID);
+  viewport_->SetViewportLayers(inner_viewport_scroll_layer_,
+                               outer_viewport_scroll_layer_);
 
   HideInnerViewportScrollbarsIfNearMinimumScale();
 
   if (!root_layer_scroll_offset_delegate_)
     return;
 
   inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
       new LayerScrollOffsetDelegateProxy(inner_viewport_scroll_layer_,
                                          root_layer_scroll_offset_delegate_,
                                          this));
 
   if (outer_viewport_scroll_layer_)
     outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
         new LayerScrollOffsetDelegateProxy(outer_viewport_scroll_layer_,
                                            root_layer_scroll_offset_delegate_,
                                            this));
 }
 
 void LayerTreeImpl::ClearViewportLayers() {
   page_scale_layer_ = NULL;
   inner_viewport_scroll_layer_ = NULL;
   outer_viewport_scroll_layer_ = NULL;
+  viewport_->SetViewportLayers(inner_viewport_scroll_layer_,
+                               outer_viewport_scroll_layer_);
 }
 
 bool LayerTreeImpl::UpdateDrawProperties(bool update_lcd_text) {
   if (!needs_update_draw_properties_)
     return true;
 
   // Calling UpdateDrawProperties must clear this flag, so there can be no
   // early outs before this.
   needs_update_draw_properties_ = false;
 
@@ skipping 1088 matching lines @@
     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
   pending_page_scale_animation_ = pending_animation.Pass();
 }
 
 scoped_ptr<PendingPageScaleAnimation>
     LayerTreeImpl::TakePendingPageScaleAnimation() {
   return pending_page_scale_animation_.Pass();
 }
 
 }  // namespace cc