Adding split view divider widget.

athena/wm/split_view_controller.cc

Index: athena/wm/split_view_controller.cc
diff --git a/athena/wm/split_view_controller.cc b/athena/wm/split_view_controller.cc
index 85db209536916f46ec72f8d59b586abf056f9e4e..72696b0e1f135097b009accdd6338bcf53135891 100644
--- a/athena/wm/split_view_controller.cc
+++ b/athena/wm/split_view_controller.cc
@@ -10,23 +10,191 @@
 #include "athena/wm/public/window_list_provider.h"
 #include "athena/wm/public/window_manager.h"
 #include "base/bind.h"
+#include "ui/aura/scoped_window_targeter.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_delegate.h"
+#include "ui/aura/window_targeter.h"
+#include "ui/base/cursor/cursor.h"
+#include "ui/base/hit_test.h"
 #include "ui/compositor/closure_animation_observer.h"
-#include "ui/compositor/layer_animation_observer.h"
+#include "ui/compositor/layer.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/events/event_handler.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/screen.h"
+#include "ui/views/widget/root_view.h"
+#include "ui/views/widget/root_view_targeter.h"
+#include "ui/views/widget/widget.h"
 #include "ui/wm/core/window_util.h"
+#include "ui/wm/public/window_types.h"
 
 namespace athena {
 
 namespace {
 
-// Returns a target transform which is suitable for animating a windows's
-// bounds.
-gfx::Transform GetTargetTransformForBoundsAnimation(const gfx::Rect& from,
-                                                    const gfx::Rect& to) {
+const int kDragHandleWidth = 4;
+const int kDragHandleHeight = 80;
+const int kDividerWidth = 6;
+
+// TODO(mfomitchev): Should this be moved to ui/views?
+
+// Always returns the same target.
+class StaticViewTargeterDelegate : public views::ViewTargeterDelegate {
+ public:
+  explicit StaticViewTargeterDelegate(views::View* target)
+      : target_(target) {}
+
+  virtual ~StaticViewTargeterDelegate() {}
+
+ private:
+  // views::ViewTargeterDelegate
+  virtual views::View* TargetForRect(
+      views::View* root, const gfx::Rect& rect) OVERRIDE {
+    return target_;
+  }
+
+  // Not owned.
+  views::View* target_;
+
+  DISALLOW_COPY_AND_ASSIGN(StaticViewTargeterDelegate);
+};
+
+// TODO(mfomitchev): This is a copy of EmptyWindowDelegate in
+// ash/root_window_controller.cc. Should we move this somewhere we can reuse in
+// both ash and athena? It looks like mojo::DummyDelegate could use this as
+// well.
+// Perhaps we could have ui/aura/empty_window_delegate.h or
+// aura::CreateEmptyWIndowDelegate() in ui/aura/window_delegate.h
+
+// A window delegate which does nothing. Used to create a window that
+// is a event target, but do nothing.
+class EmptyWindowDelegate : public aura::WindowDelegate {
+ public:
+  EmptyWindowDelegate() {}
+  virtual ~EmptyWindowDelegate() {}
+
+  // aura::WindowDelegate overrides:
+  virtual gfx::Size GetMinimumSize() const OVERRIDE {
+    return gfx::Size();
+  }
+  virtual gfx::Size GetMaximumSize() const OVERRIDE {
+    return gfx::Size();
+  }
+  virtual void OnBoundsChanged(const gfx::Rect& old_bounds,
+                               const gfx::Rect& new_bounds) OVERRIDE {
+  }
+  virtual gfx::NativeCursor GetCursor(const gfx::Point& point) OVERRIDE {
+    return gfx::kNullCursor;
+  }
+  virtual int GetNonClientComponent(
+      const gfx::Point& point) const OVERRIDE {
+    return HTNOWHERE;
+  }
+  virtual bool ShouldDescendIntoChildForEventHandling(
+      aura::Window* child,
+      const gfx::Point& location) OVERRIDE {
+    return false;
+  }
+  virtual bool CanFocus() OVERRIDE {
+    return false;
+  }
+  virtual void OnCaptureLost() OVERRIDE {
+  }
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE {
+  }
+  virtual void OnDeviceScaleFactorChanged(
+      float device_scale_factor) OVERRIDE {
+  }
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE {}

[sadrul, 2014/09/15 14:32:29]

Some have {} in the same line, some have these in separate lines. It'd be good
to be consistent (maybe run through 'git cl format')

[mfomitchev, 2014/09/15 16:37:23]

Done. All methods that don't do anything have {} on the same line now.

+  virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE {
+    delete this;
+  }
+  virtual void OnWindowTargetVisibilityChanged(bool visible) OVERRIDE {
+  }
+  virtual bool HasHitTestMask() const OVERRIDE {
+    return false;
+  }
+  virtual void GetHitTestMask(gfx::Path* mask) const OVERRIDE {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(EmptyWindowDelegate);
+
+};
+
+// Expands the effective target area of a window ensuring it is easy to touch.
+// If the window is big enough to begin with, there should be no change from
+// the default targeting behavior.
+class PriorityWindowTargeter : public aura::WindowTargeter,
+                               public aura::WindowObserver {
+ public:
+  explicit PriorityWindowTargeter(aura::Window* priority_window)
+      : priority_window_(priority_window) {
+    DCHECK(priority_window);
+    priority_window->AddObserver(this);
+  }
+
+  virtual ~PriorityWindowTargeter() {
+    priority_window_->RemoveObserver(this);
+  }
+
+ private:
+  bool ShouldProcessEvent(ui::EventType event_type) {
+    return event_type == ui::ET_TOUCH_PRESSED;
+  }
+
+  // aura::WindowTargeter:
+  virtual ui::EventTarget* FindTargetForLocatedEvent(
+        ui::EventTarget* root,
+        ui::LocatedEvent* event) OVERRIDE {
+    if (!priority_window_ || (event->type() != ui::ET_TOUCH_PRESSED))
+      return WindowTargeter::FindTargetForLocatedEvent(root, event);
+
+    gfx::Rect window_bounds = priority_window_->GetBoundsInRootWindow();
+    gfx::Transform window_transform = priority_window_->layer()->transform();
+    gfx::RectF transformed_bounds_f = window_bounds;
+    window_transform.TransformRect(&transformed_bounds_f);
+    gfx::Rect transformed_bounds = gfx::Rect(transformed_bounds_f.x(),
+                                             transformed_bounds_f.y(),
+                                             transformed_bounds_f.width(),
+                                             transformed_bounds_f.height());
+
+    gfx::Point window_center = transformed_bounds.CenterPoint();
+    gfx::Rect extension_rect = gfx::Rect(
+        window_center.x() - kMinTouchDimension / 2,
+        window_center.y() - kMinTouchDimension / 2,
+        kMinTouchDimension,
+        kMinTouchDimension);
+    gfx::Rect extended_bounds =
+        gfx::UnionRects(transformed_bounds, extension_rect);
+    if (extended_bounds.Contains(event->root_location().x(),
+                                 event->root_location().y())) {
+      root->ConvertEventToTarget(priority_window_, event);
+      return priority_window_;
+    }
+
+    return WindowTargeter::FindTargetForLocatedEvent(root, event);
+  }
+
+  // aura::WindowObserver:
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE {
+    DCHECK_EQ(window, priority_window_);
+    priority_window_->RemoveObserver(this);
+    priority_window_ = NULL;
+  }
+
+  // Minimum dimension of a target to be comfortably touchable.
+  // The effective touch target area of |priority_window_| gets expanded so
+  // that it's width and height is ayt least |kMinTouchDimension|.
+  int const kMinTouchDimension = 26;
+
+  aura::Window* priority_window_;
+
+  DISALLOW_COPY_AND_ASSIGN(PriorityWindowTargeter);
+};
+
+// Returns a target transform required to transform |from| to |to|.
+gfx::Transform GetTransformForBounds(const gfx::Rect& from,
+                                     const gfx::Rect& to) {
   gfx::Transform transform;
   transform.Translate(to.x() - from.x(), to.y() - from.y());
   transform.Scale(to.width() / static_cast<float>(from.width()),
@@ -49,7 +217,8 @@ SplitViewController::SplitViewController(
       window_list_provider_(window_list_provider),
       left_window_(NULL),
       right_window_(NULL),
-      separator_position_(0),
+      divider_position_(0),
+      divider_widget_(NULL),
       weak_factory_(this) {
 }
 
@@ -94,6 +263,8 @@ void SplitViewController::ActivateSplitMode(aura::Window* left,
     }
   }
 
+  int container_width = container_->GetBoundsInScreen().width();
+  divider_position_ = container_width / 2;
   SetState(ACTIVE);
   if (right_window_ != right) {
     right_window_ = right;
@@ -103,6 +274,7 @@ void SplitViewController::ActivateSplitMode(aura::Window* left,
     left_window_ = left;
     container_->StackChildAtTop(left_window_);
   }
+
   UpdateLayout(true);
 }
 
@@ -135,65 +307,166 @@ void SplitViewController::DeactivateSplitMode() {
   left_window_ = right_window_ = NULL;
 }
 
-gfx::Rect SplitViewController::GetLeftTargetBounds() {
-  gfx::Rect work_area =
-      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().work_area();
-  return gfx::Rect(0, 0, container_->bounds().width() / 2, work_area.height());
+void SplitViewController::InitializeDivider() {
+  CHECK(!divider_widget_);
+  CHECK(!divider_window_);
+
+  divider_window_.reset(new aura::Window(new EmptyWindowDelegate()));

[sadrul, 2014/09/15 14:32:29]

What's the purpose of |divider_window_|?

[mfomitchev, 2014/09/15 16:37:23]

It covers the empty space between two windows in split view (that is not covered
by the handle) and consumes events. If it wasn't there, the window underneath
(or the background) would show through and could be interacted with. I have
added a comment to .h to clarify.

[sadrul, 2014/09/15 16:53:31]

You don't need a separate window for this. You should have the widget span the
entire height of the screen instead. (we do this for the minimized home-card at
the bottom)

[mfomitchev, 2014/09/15 17:44:20]

If we do that, we will steal the entire right edge from the content in the left
window and the entire left edge from the content in the right window because of
the "priority" window targeting for the widget's window. I think it's good to
minimize number of pixels we steal from content. Content not chrome, and all
that.

Minimized home-card is different - the UX actually requires us to respond on any
swipe from the bottom. Plus we don't use window targeting on the minimized home
card. (Hopefully we never do that and figure out how to leverage the bezel
instead if we need to improve the targeting there).

[sadrul, 2014/09/15 17:50:25]

It still doesn't make sense to have to maintain two separate windows at the same
time for the divider. The window-targeter should be more clever about its
targeting so it doesn't steal pixels from the content.

[mfomitchev, 2014/09/15 18:34:21]

I guess we could do that..
- I guess PriorityWindowTargeter would need to take divider_view as its argument
and use its bounds within the widget to determine if the event should be
targeted to the widget's window.
- We'd need to put divider_view into another view with a BoxLayout to have it
centered within the widget.
- We'd also need to make the view targeter smarter - it shouldn't just target
the divider_view every time anymore - it would need to consider the location of
the gesture, since gestures inside the widget but away from the drag handle
should't target divider_view.
- We wouldn't be able to use WINDOW_LAYER_SOLID_COLOR anymore, so the divider
layers might become more expensive to paint/store in memory.

I undertsand it's a hassle to manipulate two divider windows instead of one in
split view controller, but we'd be adding complexity elsewhere, so I am not sure
it's a definite improvement.

If you still want me to go ahead with this change - do you mind if I make it in
a separate CL? We may not need to do the view targeting here depending on what
we do in core views.

+  divider_window_->SetType(ui::wm::WINDOW_TYPE_CONTROL);
+  divider_window_->Init(aura::WINDOW_LAYER_SOLID_COLOR);
+  divider_window_->layer()->SetColor(SK_ColorBLACK);
+  int container_height = container_->bounds().height();
+  divider_window_->SetBounds(
+      gfx::Rect(-kDividerWidth / 2, 0, kDividerWidth, container_height));
+  container_->AddChild(divider_window_.get());
+  container_->StackChildAtTop(divider_window_.get());
+
+  views::View* divider_view = CreateDragHandleView(DragHandle::HORIZONTAL,
+                                                   this,
+                                                   kDragHandleWidth,
+                                                   kDragHandleHeight,
+                                                   1);
+  divider_widget_ = new views::Widget();
+  views::Widget::InitParams params(views::Widget::InitParams::TYPE_CONTROL);
+  params.parent = container_;
+  params.accept_events = true;
+  params.activatable = views::Widget::InitParams::ACTIVATABLE_YES;

[sadrul, 2014/09/15 14:32:29]

Make this ACTIVATABLE_NO (it should still be able to receive events after that).

[mfomitchev, 2014/09/15 16:37:24]

Done. Thanks.

+  params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
+  params.bounds = gfx::Rect(-kDragHandleWidth / 2,
+                            container_height / 2 - kDragHandleHeight / 2,
+                            kDragHandleWidth,
+                            kDragHandleHeight);
+  divider_widget_->Init(params);
+  divider_widget_->SetContentsView(divider_view);
+
+  // Install a static view targeter on the root view which always targets
+  // divider_view.
+  // TODO(mfomitchev,tdanderson): This may not be needed if/when the logic
+  // in ViewTargeterDelegate::TargetForRect is changed to work better for
+  // views that are narrow in one dimension and long in another dimension.
+  views::internal::RootView* root_view =
+      static_cast<views::internal::RootView*>(divider_widget_->GetRootView());
+  views::View* target_view = divider_view;
+  views::ViewTargeter* targeter = new views::RootViewTargeter(
+          new StaticViewTargeterDelegate(target_view),
+          root_view);
+  divider_widget_->GetRootView()->SetEventTargeter(
+      scoped_ptr<views::ViewTargeter>(targeter));

[sadrul, 2014/09/15 14:32:29]

|divider_view| is the only view (other than the internal root-view; but
|divider_view| should completely overlap the root-view) in the Widget. So you
shouldn't need this targeter. What target do the gesture events go to without
this targeter?

[mfomitchev, 2014/09/15 16:37:23]

It doesn't work if I remove this view targeter. It returns the root view itself.
It rejects divider_view when the center of the touch is outside the view,
because the overlap with the touch area is <60% (the view is relatively tall). I
guess root view is its default fallback. I have expanded on the TODO comment
above this code to highlight this issue. I think we should fix this, but I'd
rather we did it outside of this CL.

[sadrul, 2014/09/15 16:53:31]

This is a pretty bad bug. You should file a crbug and reference it from the TODO
here. 

[mfomitchev, 2014/09/15 17:44:20]

Done.

 }
 
-gfx::Rect SplitViewController::GetRightTargetBounds() {
-  gfx::Rect work_area =
-      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay().work_area();
-  int container_width = container_->bounds().width();
+void SplitViewController::HideDivider() {
+  divider_widget_->Hide();
+  divider_window_->Hide();
+  window_targeter_.reset();
+}
+
+void SplitViewController::ShowDivider() {
+  divider_widget_->Show();
+  divider_window_->Show();
+  if (!window_targeter_) {
+    scoped_ptr<ui::EventTargeter> window_targeter =
+        scoped_ptr<ui::EventTargeter>(
+            new PriorityWindowTargeter(divider_widget_->GetNativeWindow()));
+    window_targeter_.reset(
+        new aura::ScopedWindowTargeter(container_, window_targeter.Pass()));
+  }
+}
+
+gfx::Rect SplitViewController::GetLeftAreaBounds() {
+  int container_height = container_->bounds().height();
   return gfx::Rect(
-      container_width / 2, 0, container_width / 2, work_area.height());
+      0, 0, divider_position_ - kDividerWidth / 2, container_height);
+}
+
+gfx::Rect SplitViewController::GetRightAreaBounds() {
+  int container_width = container_->bounds().width();
+  int container_height = container_->bounds().height();
+  return gfx::Rect(divider_position_ + kDividerWidth / 2,
+                   0,
+                   container_width - divider_position_ - kDividerWidth / 2,
+                   container_height);
 }
 
 void SplitViewController::SetState(SplitViewController::State state) {
   if (state_ == state)
     return;
 
+  if (divider_widget_ == NULL) {
+    InitializeDivider();
+  }
+
   state_ = state;
+
   ScreenManager::Get()->SetRotationLocked(state_ != INACTIVE);
+  if (state == INACTIVE)
+    HideDivider();
+  else
+    ShowDivider();
 }
 
 void SplitViewController::UpdateLayout(bool animate) {
   CHECK(left_window_);
   CHECK(right_window_);
-
   // Splitview can be activated from SplitViewController::ActivateSplitMode or
   // SplitViewController::ScrollEnd. Additionally we don't want to rotate the
   // screen while engaging splitview (i.e. state_ == SCROLLING).
   if (state_ == INACTIVE && !animate) {
-    if (!wm::IsActiveWindow(left_window_))
+    aura::Window* active_window = window_list_provider_->GetWindowList().back();
+    if (active_window != left_window_) {
       left_window_->Hide();
-    if (!wm::IsActiveWindow(right_window_))
+      right_window_->SetBounds(gfx::Rect(container_->bounds()));
+    }
+    if (active_window != right_window_) {
+      left_window_->SetBounds(gfx::Rect(container_->bounds()));
       right_window_->Hide();
-    SetWindowTransforms(gfx::Transform(), gfx::Transform(), false);
+    }
+    SetWindowTransforms(
+        gfx::Transform(), gfx::Transform(), gfx::Transform(), false);
     return;
   }
 
   left_window_->Show();
   right_window_->Show();
+  gfx::Transform divider_transform;
+  divider_transform.Translate(divider_position_, 0);
   if (state_ == ACTIVE) {
     if (animate) {
-      gfx::Transform left_transform = GetTargetTransformForBoundsAnimation(
-          left_window_->bounds(), GetLeftTargetBounds());
-      gfx::Transform right_transform = GetTargetTransformForBoundsAnimation(
-          right_window_->bounds(), GetRightTargetBounds());
-      SetWindowTransforms(left_transform, right_transform, true);
+      gfx::Transform left_transform =
+          GetTransformForBounds(left_window_->bounds(), GetLeftAreaBounds());
+      gfx::Transform right_transform =
+          GetTransformForBounds(right_window_->bounds(), GetRightAreaBounds());
+      SetWindowTransforms(
+          left_transform, right_transform, divider_transform, true);
     } else {
-      left_window_->SetBounds(GetLeftTargetBounds());
-      right_window_->SetBounds(GetRightTargetBounds());
-      SetWindowTransforms(gfx::Transform(), gfx::Transform(), false);
+      left_window_->SetBounds(GetLeftAreaBounds());
+      right_window_->SetBounds(GetRightAreaBounds());
+      SetWindowTransforms(
+          gfx::Transform(), gfx::Transform(), divider_transform, false);
     }
   } else {
     gfx::Transform left_transform;
-    left_transform.Translate(separator_position_ - container_->bounds().width(),
-                             0);
     gfx::Transform right_transform;
-    right_transform.Translate(separator_position_, 0);
-    SetWindowTransforms(left_transform, right_transform, animate);
+    gfx::Rect left_area_bounds = GetLeftAreaBounds();
+    gfx::Rect right_area_bounds = GetRightAreaBounds();
+    // If the width of the window is greater than the width of the area which it
+    // is supposed to occupy - translate the window. Otherwise scale the window
+    // up to fill the target area.
+    if (left_window_->bounds().width() >= left_area_bounds.width()) {
+      left_transform.Translate(
+          left_area_bounds.right() - left_window_->bounds().right(), 0);
+    } else {
+      left_transform =
+          GetTransformForBounds(left_window_->bounds(), left_area_bounds);
+    }
+    if (right_window_->bounds().width() >= right_area_bounds.width()) {
+      right_transform.Translate(
+          right_area_bounds.x() - right_window_->bounds().x(), 0);
+    } else {
+      right_transform =
+          GetTransformForBounds(right_window_->bounds(), right_area_bounds);
+    }
+    SetWindowTransforms(
+        left_transform, right_transform, divider_transform, animate);
   }
   // Note: |left_window_| and |right_window_| may be NULL if calling
   // SetWindowTransforms():
@@ -204,6 +477,7 @@ void SplitViewController::UpdateLayout(bool animate) {
 void SplitViewController::SetWindowTransforms(
     const gfx::Transform& left_transform,
     const gfx::Transform& right_transform,
+    const gfx::Transform& divider_transform,
     bool animate) {
   if (animate) {
     ui::ScopedLayerAnimationSettings left_settings(
@@ -212,6 +486,18 @@ void SplitViewController::SetWindowTransforms(
         ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
     left_window_->SetTransform(left_transform);
 
+    ui::ScopedLayerAnimationSettings divider_widget_settings(
+        divider_widget_->GetNativeWindow()->layer()->GetAnimator());
+    divider_widget_settings.SetPreemptionStrategy(
+        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+    divider_widget_->GetNativeWindow()->SetTransform(divider_transform);
+
+    ui::ScopedLayerAnimationSettings divider_layer_settings(
+        divider_window_->layer()->GetAnimator());
+    divider_layer_settings.SetPreemptionStrategy(
+        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+    divider_window_->SetTransform(divider_transform);
+
     ui::ScopedLayerAnimationSettings right_settings(
         right_window_->layer()->GetAnimator());
     right_settings.SetPreemptionStrategy(
@@ -223,6 +509,8 @@ void SplitViewController::SetWindowTransforms(
   } else {
     left_window_->SetTransform(left_transform);
     right_window_->SetTransform(right_transform);
+    divider_widget_->GetNativeWindow()->SetTransform(divider_transform);
+    divider_window_->SetTransform(divider_transform);
   }
 }
 
@@ -243,7 +531,7 @@ void SplitViewController::UpdateSeparatorPositionFromScrollDelta(float delta) {
   const gfx::Rect& display_bounds =
       screen->GetDisplayNearestWindow(container_).bounds();
   gfx::Rect container_bounds = container_->GetBoundsInScreen();
-  separator_position_ =
+  divider_position_ =
       delta > 0 ? ((int)delta) + display_bounds.x() - container_bounds.x()
                 : display_bounds.right() - container_bounds.x() + delta;
 }
@@ -255,13 +543,13 @@ void SplitViewController::ScrollBegin(BezelController::Bezel bezel,
                                       float delta) {
   if (!CanScroll())
     return;
+
   SetState(SCROLLING);
 
   aura::Window::Windows windows = window_list_provider_->GetWindowList();
   CHECK(windows.size() >= 2);
   aura::Window::Windows::const_reverse_iterator iter = windows.rbegin();
   aura::Window* current_window = *(iter);
-  CHECK(wm::IsActiveWindow(current_window));
 
   if (delta > 0) {
     right_window_ = current_window;
@@ -286,16 +574,16 @@ void SplitViewController::ScrollEnd() {
   // we would go into the split view mode.
   const int kMaxDistanceFromMiddle = 120;
   int container_width = container_->GetBoundsInScreen().width();
-  if (std::abs(container_width / 2 - separator_position_) <=
+  if (std::abs(container_width / 2 - divider_position_) <=
       kMaxDistanceFromMiddle) {
+    divider_position_ = container_width / 2;
     SetState(ACTIVE);
-    separator_position_ = container_width / 2;
-  } else if (separator_position_ < container_width / 2) {
-    separator_position_ = 0;
+  } else if (divider_position_ < container_width / 2) {
+    divider_position_ = 0;
     SetState(INACTIVE);
     wm::ActivateWindow(right_window_);
   } else {
-    separator_position_ = container_width;
+    divider_position_ = container_width;
     SetState(INACTIVE);
     wm::ActivateWindow(left_window_);
   }
@@ -318,4 +606,53 @@ bool SplitViewController::CanScroll() {
   return result;
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// ScrollHandle::ScrollDelegate:
+
+void SplitViewController::HandleScrollBegin(float delta) {
+  CHECK(state_ == ACTIVE);
+  state_ = SCROLLING;
+  divider_position_ = delta + divider_position_;
+  UpdateLayout(false);
+}
+
+void SplitViewController::HandleScrollEnd() {
+  ScrollEnd();
+}
+
+void SplitViewController::HandleScrollUpdate(float delta) {
+  if (state_ != SCROLLING)
+    return;
+  divider_position_ = delta + container_->GetBoundsInScreen().width() / 2;
+  UpdateLayout(false);
+}
+
+bool SplitViewController::HandleCanScroll() {
+  CHECK(IsLandscapeOrientation(gfx::Screen::GetNativeScreen()
+                                   ->GetDisplayNearestWindow(container_)
+                                   .rotation()));
+  return true;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// WindowManagerObserver:
+
+void SplitViewController::OnOverviewModeEnter() {
+  if (divider_widget_) {

[sadrul, 2014/09/15 14:32:29]

Remove {}

[mfomitchev, 2014/09/15 16:37:24]

Done.

+    HideDivider();
+  }
+}
+
+void SplitViewController::OnOverviewModeExit() {
+  if (state_ != INACTIVE) {

[sadrul, 2014/09/15 14:32:29]

ditto

[mfomitchev, 2014/09/15 16:37:24]

Done.

+    ShowDivider();
+  }
+}
+
+void SplitViewController::OnSplitViewModeEnter() {
+}
+
+void SplitViewController::OnSplitViewModeExit() {
+}
+
 }  // namespace athena