Consolidate content fling implementations

athena/wm/window_overview_mode.cc

 // Copyright 2014 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 "athena/wm/window_overview_mode.h"
 
 #include <algorithm>
 #include <functional>
 #include <vector>
 
@@ skipping 678 matching lines @@
         RemoveAnimationObserver();
         gesture->SetHandled();
       }
       dragged_window_ = NULL;
     }
   }
 
   // ui::CompositorAnimationObserver:
   virtual void OnAnimationStep(base::TimeTicks timestamp) override {
     CHECK(fling_);
-    if (fling_->start_timestamp() > timestamp)
-      return;
-    gfx::Vector2dF scroll = fling_->GetScrollAmountAtTime(timestamp);
-    if (scroll.IsZero()) {
+    gfx::Vector2dF delta;
+    bool fling_active = fling_->ComputeScrollDeltaAtTime(timestamp, &delta);
+
+    if (!scroll.IsZero())
+      DoScroll(delta.y());
+
+    if (!fling_active) {
       fling_.reset();
       RemoveAnimationObserver();
-    } else {
-      DoScroll(scroll.y());
     }
   }
 
   // WindowListProviderObserver:
   virtual void OnWindowStackingChanged() override {
     // Recompute the states of all windows. There isn't enough information at
     // this point to do anything more clever.
     ComputeTerminalStatesForAllWindows();
     SetInitialWindowStates();
   }
@@ skipping 59 matching lines @@
     aura::Window* container,
     WindowListProvider* window_list_provider,
     SplitViewController* split_view_controller,
     WindowOverviewModeDelegate* delegate) {
   return scoped_ptr<WindowOverviewMode>(
       new WindowOverviewModeImpl(container, window_list_provider,
                                  split_view_controller, delegate));
 }
 
 }  // namespace athena