Connect LTHI::ScrollAnimated to cc::Viewport

cc/trees/layer_tree_host_impl.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <stddef.h>
 
 #include <set>
@@ skipping 518 matching lines @@
   virtual ResourceId ResourceIdForUIResource(UIResourceId uid) const;
 
   virtual bool IsUIResourceOpaque(UIResourceId uid) const;
 
   struct UIResourceData {
     ResourceId resource_id;
     gfx::Size size;
     bool opaque;
   };
 
+  struct ScrollAmount {

[bokan, 2016/04/06 13:35:52]

I don't like this, there's opportunity for delta and target_offset to point to
different locations and it makes it harder to think about how things will work
given a ScrollAmount. Why not just use a delta and convert to an offset using
clamp(current_offset + delta)?

[ymalik, 2016/04/06 15:33:45]

You're right, it's not used often enough to justify. Done!

+    ScrollAmount(gfx::Vector2dF delta, gfx::ScrollOffset offset)
+        : delta(delta), target_offset(offset) {}
+    gfx::Vector2dF delta;
+    gfx::ScrollOffset target_offset;
+  };
+
+  // Returns the amount of delta that can be applied to scroll_node, taking
+  // page scale into account.
+  ScrollAmount ComputeScrollDelta(ScrollNode* scroll_node,
+                                  const gfx::Vector2dF& delta);
+
   void ScheduleMicroBenchmark(scoped_ptr<MicroBenchmarkImpl> benchmark);
 
   CompositorFrameMetadata MakeCompositorFrameMetadata() const;
   // Viewport rectangle and clip in nonflipped window space.  These rects
   // should only be used by Renderer subclasses to populate glViewport/glClip
   // and their software-mode equivalents.
   gfx::Rect DeviceViewport() const;
   gfx::Rect DeviceClip() const;
 
   // When a SwapPromiseMonitor is created on the impl thread, it calls
@@ skipping 60 matching lines @@
     return task_runner_provider_->HasImplThread()
                ? task_runner_provider_->ImplThreadTaskRunner()
                : task_runner_provider_->MainThreadTaskRunner();
   }
 
   InputHandler::ScrollStatus TryScroll(const gfx::PointF& screen_space_point,
                                        InputHandler::ScrollInputType type,
                                        const ScrollTree& scroll_tree,
                                        ScrollNode* scroll_node) const;
 
+  // Returns true if a scroll offset animation is created and false if we scroll
+  // by the desired amount without an animation.
+  bool ScrollAnimationCreate(ScrollNode* scroll_node,
+                             const ScrollAmount& scroll_amount);
+
  protected:
   LayerTreeHostImpl(
       const LayerTreeSettings& settings,
       LayerTreeHostImplClient* client,
       TaskRunnerProvider* task_runner_provider,
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
       TaskGraphRunner* task_graph_runner,
       int id);
@@ skipping 78 matching lines @@
   void MarkUIResourceNotEvicted(UIResourceId uid);
   void ClearUIResources();
 
   void NotifySwapPromiseMonitorsOfSetNeedsRedraw();
   void NotifySwapPromiseMonitorsOfForwardingToMainThread();
 
   void UpdateRootLayerStateForSynchronousInputHandler();
 
   void ScrollAnimationAbort(LayerImpl* layer_impl);
 
-  void ScrollAnimationCreate(ScrollNode* scroll_node,
-                             const gfx::ScrollOffset& target_offset,
-                             const gfx::ScrollOffset& current_offset);
   bool ScrollAnimationUpdateTarget(ScrollNode* scroll_node,
                                    const gfx::Vector2dF& scroll_delta);
 
   using UIResourceMap = std::unordered_map<UIResourceId, UIResourceData>;
   UIResourceMap ui_resource_map_;
 
   // Resources that were evicted by EvictAllUIResources. Resources are removed
   // from this when they are touched by a create or destroy from the UI resource
   // request queue.
   std::set<UIResourceId> evicted_ui_resources_;
@@ skipping 118 matching lines @@
   scoped_ptr<FrameTimingTracker> frame_timing_tracker_;
 
   scoped_ptr<Viewport> viewport_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_