Translate the overscroll elasticity layer by the overscroll amount

Add a synced property, elastic_overscroll, similar to page_scale_factor.

Use this property to translate the overscroll elasticity layer.

With this in place, the overscroll effect works most of the time,
when using impl-thread events.

Originally committed at r306991, reverted at r306995 due to ASAN break
due to LTI::overscroll_elasticity_layer_ not being initialized.

BUG=133097
TBR=aelias

Review URL: https://codereview.chromium.org/749393005

Cr-Commit-Position: refs/heads/master@{#307057}

10 files changed, 82 insertions, 20 deletions

diff --git a/cc/input/scroll_elasticity_helper.cc b/cc/input/scroll_elasticity_helper.cc
index 54da888..6a38e4b3 100644
--- a/cc/input/scroll_elasticity_helper.cc
+++ b/cc/input/scroll_elasticity_helper.cc
@@ -32,6 +32,7 @@ bool ScrollElasticityHelper::AllowsVerticalStretching() {
 }
 
 gfx::Vector2dF ScrollElasticityHelper::StretchAmount() {
+  // TODO(ccameron): Use the value of active_tree->elastic_overscroll directly
   return stretch_offset_;
 }
 
@@ -63,7 +64,7 @@ bool ScrollElasticityHelper::CanScrollVertically() {
 
 gfx::Vector2dF ScrollElasticityHelper::AbsoluteScrollPosition() {
   // TODO(ccameron): This is function is redundant and may be removed.
-  return stretch_offset_;
+  return StretchAmount();
 }
 
 void ScrollElasticityHelper::ImmediateScrollBy(const gfx::Vector2dF& scroll) {
@@ -73,9 +74,14 @@ void ScrollElasticityHelper::ImmediateScrollBy(const gfx::Vector2dF& scroll) {
 void ScrollElasticityHelper::ImmediateScrollByWithoutContentEdgeConstraints(
     const gfx::Vector2dF& scroll) {
   stretch_offset_ += scroll;
-
-  // TODO(ccameron): Update the transform of the appropriate layer in the
-  // LayerTreeHostImpl, and request that a frame be drawn.
+  // TODO(ccameron): Use the value of active_tree->elastic_overscroll directly
+  // Note that this assumes that this property's true value is ever changed
+  // by the impl thread. While this is true, it is redundant state.
+  layer_tree_host_impl_->active_tree()->elastic_overscroll()->SetCurrent(
+      -stretch_offset_);
+  layer_tree_host_impl_->active_tree()->set_needs_update_draw_properties();
+  layer_tree_host_impl_->SetNeedsCommit();
+  layer_tree_host_impl_->SetNeedsRedraw();
 }
 
 void ScrollElasticityHelper::StartSnapRubberbandTimer() {
diff --git a/cc/input/top_controls_manager_unittest.cc b/cc/input/top_controls_manager_unittest.cc
index a209012..0be40ca 100644
--- a/cc/input/top_controls_manager_unittest.cc
+++ b/cc/input/top_controls_manager_unittest.cc
@@ -32,7 +32,8 @@ class MockTopControlsManagerClient : public TopControlsManagerClient {
         top_controls_show_threshold_(top_controls_show_threshold),
         top_controls_hide_threshold_(top_controls_hide_threshold) {
     active_tree_ =
-        LayerTreeImpl::create(&host_impl_, new SyncedProperty<ScaleGroup>);
+        LayerTreeImpl::create(&host_impl_, new SyncedProperty<ScaleGroup>,
+                              new SyncedElasticOverscroll);
     root_scroll_layer_ = LayerImpl::Create(active_tree_.get(), 1);
   }
 
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 361fae1..22b1196 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -363,6 +363,9 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
 
   sync_tree->PushPageScaleFromMainThread(
       page_scale_factor_, min_page_scale_factor_, max_page_scale_factor_);
+  sync_tree->elastic_overscroll()->PushFromMainThread(elastic_overscroll_);
+  if (sync_tree->IsActiveTree())
+    sync_tree->elastic_overscroll()->PushPendingToActive();
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 
@@ -875,6 +878,7 @@ bool LayerTreeHost::UpdateLayers(Layer* root_layer,
     LayerTreeHostCommon::CalcDrawPropsMainInputs inputs(
         root_layer, device_viewport_size(), gfx::Transform(),
         device_scale_factor_, page_scale_factor_, page_scale_layer,
+        elastic_overscroll_, overscroll_elasticity_layer_.get(),
         GetRendererCapabilities().max_texture_size, settings_.can_use_lcd_text,
         settings_.layers_always_allowed_lcd_text,
         can_render_to_separate_surface,
@@ -1126,9 +1130,8 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
   }
 
   if (!inner_viewport_scroll_delta.IsZero() ||
-      !outer_viewport_scroll_delta.IsZero() ||
-      info->page_scale_delta != 1.f ||
-      info->top_controls_delta) {
+      !outer_viewport_scroll_delta.IsZero() || info->page_scale_delta != 1.f ||
+      !info->elastic_overscroll_delta.IsZero() || info->top_controls_delta) {
     // Preemptively apply the scroll offset and scale delta here before sending
     // it to the client.  If the client comes back and sets it to the same
     // value, then the layer can early out without needing a full commit.
@@ -1147,12 +1150,15 @@ void LayerTreeHost::ApplyScrollAndScale(ScrollAndScaleSet* info) {
     }
 
     ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
+    elastic_overscroll_ += info->elastic_overscroll_delta;
     if (!settings_.use_pinch_virtual_viewport) {
       client_->ApplyViewportDeltas(
           inner_viewport_scroll_delta + outer_viewport_scroll_delta,
           info->page_scale_delta,
           info->top_controls_delta);
     } else {
+      // TODO(ccameron): pass the elastic overscroll here so that input events
+      // may be translated appropriately.
       client_->ApplyViewportDeltas(
           inner_viewport_scroll_delta,
           outer_viewport_scroll_delta,
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 9d758c8..75165ad 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -223,6 +223,7 @@ class CC_EXPORT LayerTreeHost {
                                    float min_page_scale_factor,
                                    float max_page_scale_factor);
   float page_scale_factor() const { return page_scale_factor_; }
+  gfx::Vector2dF elastic_overscroll() const { return elastic_overscroll_; }
 
   SkColor background_color() const { return background_color_; }
   void set_background_color(SkColor color) { background_color_ = color; }
@@ -428,6 +429,7 @@ class CC_EXPORT LayerTreeHost {
   float page_scale_factor_;
   float min_page_scale_factor_;
   float max_page_scale_factor_;
+  gfx::Vector2dF elastic_overscroll_;
   bool has_gpu_rasterization_trigger_;
   bool content_is_suitable_for_gpu_rasterization_;
   bool gpu_rasterization_histogram_recorded_;
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 3b4de1d..9a9650f 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -1268,6 +1268,8 @@ struct SubtreeGlobals {
   float device_scale_factor;
   float page_scale_factor;
   const LayerType* page_scale_application_layer;
+  gfx::Vector2dF elastic_overscroll;
+  const LayerType* elastic_overscroll_application_layer;
   bool can_adjust_raster_scales;
   bool can_render_to_separate_surface;
   bool layers_always_allowed_lcd_text;
@@ -2121,6 +2123,10 @@ static void CalculateDrawPropertiesInternal(
           globals.page_scale_factor);
       data_for_children.in_subtree_of_page_scale_application_layer = true;
     }
+    if (layer == globals.elastic_overscroll_application_layer) {
+      data_for_children.parent_matrix.Translate(globals.elastic_overscroll.x(),
+                                                globals.elastic_overscroll.y());
+    }
 
     // Flatten to 2D if the layer doesn't preserve 3D.
     if (layer->should_flatten_transform())
@@ -2399,6 +2405,9 @@ static void ProcessCalcDrawPropsInputs(
       inputs.device_scale_factor * device_transform_scale;
   globals->page_scale_factor = inputs.page_scale_factor;
   globals->page_scale_application_layer = inputs.page_scale_application_layer;
+  globals->elastic_overscroll = inputs.elastic_overscroll;
+  globals->elastic_overscroll_application_layer =
+      inputs.elastic_overscroll_application_layer;
   globals->can_render_to_separate_surface =
       inputs.can_render_to_separate_surface;
   globals->can_adjust_raster_scales = inputs.can_adjust_raster_scales;
diff --git a/cc/trees/layer_tree_host_common.h b/cc/trees/layer_tree_host_common.h
index 349b341..81aca55 100644
--- a/cc/trees/layer_tree_host_common.h
+++ b/cc/trees/layer_tree_host_common.h
@@ -38,6 +38,8 @@ class CC_EXPORT LayerTreeHostCommon {
                         float device_scale_factor,
                         float page_scale_factor,
                         const LayerType* page_scale_application_layer,
+                        const gfx::Vector2dF& elastic_overscroll,
+                        const LayerType* elastic_overscroll_application_layer,
                         int max_texture_size,
                         bool can_use_lcd_text,
                         bool layers_always_allowed_lcd_text,
@@ -51,6 +53,9 @@ class CC_EXPORT LayerTreeHostCommon {
           device_scale_factor(device_scale_factor),
           page_scale_factor(page_scale_factor),
           page_scale_application_layer(page_scale_application_layer),
+          elastic_overscroll(elastic_overscroll),
+          elastic_overscroll_application_layer(
+              elastic_overscroll_application_layer),
           max_texture_size(max_texture_size),
           can_use_lcd_text(can_use_lcd_text),
           layers_always_allowed_lcd_text(layers_always_allowed_lcd_text),
@@ -66,6 +71,8 @@ class CC_EXPORT LayerTreeHostCommon {
     float device_scale_factor;
     float page_scale_factor;
     const LayerType* page_scale_application_layer;
+    gfx::Vector2dF elastic_overscroll;
+    const LayerType* elastic_overscroll_application_layer;
     int max_texture_size;
     bool can_use_lcd_text;
     bool layers_always_allowed_lcd_text;
@@ -145,6 +152,7 @@ struct CC_EXPORT ScrollAndScaleSet {
 
   std::vector<LayerTreeHostCommon::ScrollUpdateInfo> scrolls;
   float page_scale_delta;
+  gfx::Vector2dF elastic_overscroll_delta;
   float top_controls_delta;
   ScopedPtrVector<SwapPromise> swap_promises;
 };
@@ -223,6 +231,8 @@ LayerTreeHostCommon::CalcDrawPropsInputsForTesting<LayerType,
           1.f,
           1.f,
           NULL,
+          gfx::Vector2dF(),
+          NULL,
           std::numeric_limits<int>::max() / 2,
           false,
           false,
@@ -248,6 +258,8 @@ LayerTreeHostCommon::CalcDrawPropsInputsForTesting<LayerType,
           1.f,
           1.f,
           NULL,
+          gfx::Vector2dF(),
+          NULL,
           std::numeric_limits<int>::max() / 2,
           false,
           false,
diff --git a/cc/trees/layer_tree_host_common_perftest.cc b/cc/trees/layer_tree_host_common_perftest.cc
index 2fd2146..ab72cf9 100644
--- a/cc/trees/layer_tree_host_common_perftest.cc
+++ b/cc/trees/layer_tree_host_common_perftest.cc
@@ -96,6 +96,8 @@ class CalcDrawPropsMainTest : public LayerTreeHostCommonPerfTest {
           layer_tree_host()->device_viewport_size(), gfx::Transform(),
           layer_tree_host()->device_scale_factor(),
           layer_tree_host()->page_scale_factor(),
+          layer_tree_host()->overscroll_elasticity_layer(),
+          layer_tree_host()->elastic_overscroll(),
           layer_tree_host()->page_scale_layer(), max_texture_size,
           layer_tree_host()->settings().can_use_lcd_text,
           layer_tree_host()->settings().layers_always_allowed_lcd_text,
@@ -148,7 +150,9 @@ class CalcDrawPropsImplTest : public LayerTreeHostCommonPerfTest {
         active_tree->root_layer(), active_tree->DrawViewportSize(),
         host_impl->DrawTransform(), active_tree->device_scale_factor(),
         active_tree->current_page_scale_factor(),
-        active_tree->InnerViewportContainerLayer(), max_texture_size,
+        active_tree->InnerViewportContainerLayer(),
+        active_tree->elastic_overscroll()->Current(active_tree->IsActiveTree()),
+        active_tree->overscroll_elasticity_layer(), max_texture_size,
         host_impl->settings().can_use_lcd_text,
         host_impl->settings().layers_always_allowed_lcd_text,
         can_render_to_separate_surface,
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 566fb57..307078f 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -237,7 +237,8 @@ LayerTreeHostImpl::LayerTreeHostImpl(
   SetDebugState(settings.initial_debug_state);
 
   // LTHI always has an active tree.
-  active_tree_ = LayerTreeImpl::create(this, new SyncedProperty<ScaleGroup>());
+  active_tree_ = LayerTreeImpl::create(this, new SyncedProperty<ScaleGroup>(),
+                                       new SyncedElasticOverscroll);
 
   TRACE_EVENT_OBJECT_CREATED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("cc.debug"), "cc::LayerTreeHostImpl", id_);
@@ -1101,8 +1102,8 @@ void LayerTreeHostImpl::BlockNotifyReadyToActivateForTesting(bool block) {
 void LayerTreeHostImpl::ResetTreesForTesting() {
   if (active_tree_)
     active_tree_->DetachLayerTree();
-  active_tree_ =
-      LayerTreeImpl::create(this, active_tree()->page_scale_factor());
+  active_tree_ = LayerTreeImpl::create(this, active_tree()->page_scale_factor(),
+                                       active_tree()->elastic_overscroll());
   if (pending_tree_)
     pending_tree_->DetachLayerTree();
   pending_tree_ = nullptr;
@@ -1748,7 +1749,8 @@ void LayerTreeHostImpl::CreatePendingTree() {
     recycle_tree_.swap(pending_tree_);
   else
     pending_tree_ =
-        LayerTreeImpl::create(this, active_tree()->page_scale_factor());
+        LayerTreeImpl::create(this, active_tree()->page_scale_factor(),
+                              active_tree()->elastic_overscroll());
 
   // Update the delta from the active tree, which may have
   // adjusted its delta prior to the pending tree being created.
@@ -3022,6 +3024,8 @@ scoped_ptr<ScrollAndScaleSet> LayerTreeHostImpl::ProcessScrollDeltas() {
   CollectScrollDeltas(scroll_info.get(), active_tree_->root_layer());
   scroll_info->page_scale_delta =
       active_tree_->page_scale_factor()->PullDeltaForMainThread();
+  scroll_info->elastic_overscroll_delta =
+      active_tree_->elastic_overscroll()->PullDeltaForMainThread();
   scroll_info->swap_promises.swap(swap_promises_for_main_thread_scroll_update_);
   scroll_info->top_controls_delta = active_tree()->top_controls_delta();
   active_tree_->set_sent_top_controls_delta(scroll_info->top_controls_delta);
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 3a4d36d..6a88834 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -75,7 +75,8 @@ class LayerScrollOffsetDelegateProxy : public LayerImpl::ScrollOffsetDelegate {
 
 LayerTreeImpl::LayerTreeImpl(
     LayerTreeHostImpl* layer_tree_host_impl,
-    scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor)
+    scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+    scoped_refptr<SyncedElasticOverscroll> elastic_overscroll)
     : layer_tree_host_impl_(layer_tree_host_impl),
       source_frame_number_(-1),
       hud_layer_(0),
@@ -83,12 +84,14 @@ LayerTreeImpl::LayerTreeImpl(
       root_layer_scroll_offset_delegate_(NULL),
       background_color_(0),
       has_transparent_background_(false),
+      overscroll_elasticity_layer_(NULL),
       page_scale_layer_(NULL),
       inner_viewport_scroll_layer_(NULL),
       outer_viewport_scroll_layer_(NULL),
       page_scale_factor_(page_scale_factor),
       min_page_scale_factor_(0),
       max_page_scale_factor_(0),
+      elastic_overscroll_(elastic_overscroll),
       scrolling_layer_id_from_previous_tree_(0),
       contents_textures_purged_(false),
       viewport_size_invalid_(false),
@@ -230,6 +233,7 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   // tree so only the limits need to be provided.
   target_tree->PushPageScaleFactorAndLimits(nullptr, min_page_scale_factor(),
                                             max_page_scale_factor());
+  target_tree->elastic_overscroll()->PushPendingToActive();
 
   target_tree->pending_page_scale_animation_ =
       pending_page_scale_animation_.Pass();
@@ -428,6 +432,7 @@ void LayerTreeImpl::ApplySentScrollAndScaleDeltasFromAbortedCommit() {
   DCHECK(IsActiveTree());
 
   page_scale_factor()->AbortCommit();
+  elastic_overscroll()->AbortCommit();
 
   top_controls_content_offset_ += sent_top_controls_delta_;
   top_controls_delta_ -= sent_top_controls_delta_;
@@ -524,8 +529,9 @@ bool LayerTreeImpl::UpdateDrawProperties() {
         root_layer(), DrawViewportSize(),
         layer_tree_host_impl_->DrawTransform(), device_scale_factor(),
         current_page_scale_factor(), page_scale_layer,
-        resource_provider()->max_texture_size(), settings().can_use_lcd_text,
-        settings().layers_always_allowed_lcd_text,
+        elastic_overscroll()->Current(IsActiveTree()),
+        overscroll_elasticity_layer_, resource_provider()->max_texture_size(),
+        settings().can_use_lcd_text, settings().layers_always_allowed_lcd_text,
         can_render_to_separate_surface,
         settings().layer_transforms_should_scale_layer_contents,
         &render_surface_layer_list_, render_surface_layer_list_id_);
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index d16234b..46b8312 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -50,14 +50,16 @@ struct RendererCapabilities;
 struct SelectionHandle;
 
 typedef std::list<UIResourceRequest> UIResourceRequestQueue;
+typedef SyncedProperty<AdditionGroup<gfx::Vector2dF>> SyncedElasticOverscroll;
 
 class CC_EXPORT LayerTreeImpl {
  public:
   static scoped_ptr<LayerTreeImpl> create(
       LayerTreeHostImpl* layer_tree_host_impl,
-      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor) {
-    return make_scoped_ptr(
-        new LayerTreeImpl(layer_tree_host_impl, page_scale_factor));
+      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedElasticOverscroll> elastic_overscroll) {
+    return make_scoped_ptr(new LayerTreeImpl(
+        layer_tree_host_impl, page_scale_factor, elastic_overscroll));
   }
   virtual ~LayerTreeImpl();
 
@@ -179,6 +181,13 @@ class CC_EXPORT LayerTreeImpl {
   SyncedProperty<ScaleGroup>* page_scale_factor();
   const SyncedProperty<ScaleGroup>* page_scale_factor() const;
 
+  SyncedElasticOverscroll* elastic_overscroll() {
+    return elastic_overscroll_.get();
+  }
+  const SyncedElasticOverscroll* elastic_overscroll() const {
+    return elastic_overscroll_.get();
+  }
+
   // Updates draw properties and render surface layer list, as well as tile
   // priorities. Returns false if it was unable to update.
   bool UpdateDrawProperties();
@@ -325,7 +334,8 @@ class CC_EXPORT LayerTreeImpl {
  protected:
   explicit LayerTreeImpl(
       LayerTreeHostImpl* layer_tree_host_impl,
-      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor);
+      scoped_refptr<SyncedProperty<ScaleGroup>> page_scale_factor,
+      scoped_refptr<SyncedElasticOverscroll> elastic_overscroll);
   void ReleaseResourcesRecursive(LayerImpl* current);
   float ClampPageScaleFactorToLimits(float page_scale_factor) const;
   void PushPageScaleFactorAndLimits(const float* page_scale_factor,
@@ -360,6 +370,8 @@ class CC_EXPORT LayerTreeImpl {
   float min_page_scale_factor_;
   float max_page_scale_factor_;
 
+  scoped_refptr<SyncedElasticOverscroll> elastic_overscroll_;
+
   typedef base::hash_map<int, LayerImpl*> LayerIdMap;
   LayerIdMap layer_id_map_;