views: Fix touch-scrolling submenus.

Update the views::ScrollDelegate::OnScroll() interface to return
whether the content was scrolled or not. Use this return value to
determine whether to consume touch-scroll events or not.

BUG=141496

Review URL: https://codereview.chromium.org/11442069

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@172801 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 25 insertions, 17 deletions

diff --git a/ui/views/animation/scroll_animator.h b/ui/views/animation/scroll_animator.h
index 8cc58e4..35e159b 100644
--- a/ui/views/animation/scroll_animator.h
+++ b/ui/views/animation/scroll_animator.h
@@ -18,7 +18,8 @@ namespace views {
 
 class VIEWS_EXPORT ScrollDelegate {
  public:
-  virtual void OnScroll(float dx, float dy) = 0;
+  // Returns true if the content was actually scrolled, false otherwise.
+  virtual bool OnScroll(float dx, float dy) = 0;
 
  protected:
   ~ScrollDelegate() {}
diff --git a/ui/views/controls/menu/submenu_view.cc b/ui/views/controls/menu/submenu_view.cc
index 0ace2d1..fe96339 100644
--- a/ui/views/controls/menu/submenu_view.cc
+++ b/ui/views/controls/menu/submenu_view.cc
@@ -267,7 +267,7 @@ void SubmenuView::OnGestureEvent(ui::GestureEvent* event) {
       scroll_animator_->Stop();
       break;
     case ui::ET_GESTURE_SCROLL_UPDATE:
-      OnScroll(0, event->details().scroll_y());
+      handled = OnScroll(0, event->details().scroll_y());
       break;
     case ui::ET_GESTURE_SCROLL_END:
       break;
@@ -442,17 +442,20 @@ gfx::Rect SubmenuView::CalculateDropIndicatorBounds(
   }
 }
 
-void SubmenuView::OnScroll(float dx, float dy) {
+bool SubmenuView::OnScroll(float dx, float dy) {
   const gfx::Rect& vis_bounds = GetVisibleBounds();
   const gfx::Rect& full_bounds = bounds();
   int x = vis_bounds.x();
   int y = vis_bounds.y() - static_cast<int>(dy);
   // clamp y to [0, full_height - vis_height)
-  y = std::max(y, 0);
   y = std::min(y, full_bounds.height() - vis_bounds.height() - 1);
+  y = std::max(y, 0);
   gfx::Rect new_vis_bounds(x, y, vis_bounds.width(), vis_bounds.height());
-  if (new_vis_bounds != vis_bounds)
+  if (new_vis_bounds != vis_bounds) {
     ScrollRectToVisible(new_vis_bounds);
+    return true;
+  }
+  return false;
 }
 
 }  // namespace views
diff --git a/ui/views/controls/menu/submenu_view.h b/ui/views/controls/menu/submenu_view.h
index a83c5a9a..ae4c0e9 100644
--- a/ui/views/controls/menu/submenu_view.h
+++ b/ui/views/controls/menu/submenu_view.h
@@ -173,7 +173,7 @@ class VIEWS_EXPORT SubmenuView : public View,
                                          MenuDelegate::DropPosition position);
 
   // Implementation of ScrollDelegate
-  virtual void OnScroll(float dx, float dy) OVERRIDE;
+  virtual bool OnScroll(float dx, float dy) OVERRIDE;
 
   // Parent menu item.
   MenuItemView* parent_menu_item_;
diff --git a/ui/views/controls/scrollbar/base_scroll_bar.cc b/ui/views/controls/scrollbar/base_scroll_bar.cc
index 6643735..70287d4 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.cc
+++ b/ui/views/controls/scrollbar/base_scroll_bar.cc
@@ -99,14 +99,19 @@ void BaseScrollBar::ScrollToThumbPosition(int thumb_position,
   SchedulePaint();
 }
 
-void BaseScrollBar::ScrollByContentsOffset(int contents_offset) {
+bool BaseScrollBar::ScrollByContentsOffset(int contents_offset) {
+  int old_offset = contents_scroll_offset_;
   contents_scroll_offset_ -= contents_offset;
   if (contents_scroll_offset_ < GetMinPosition()) {
     contents_scroll_offset_ = GetMinPosition();
   } else if (contents_scroll_offset_ > GetMaxPosition()) {
     contents_scroll_offset_ = GetMaxPosition();
   }
+  if (old_offset == contents_scroll_offset_)
+    return false;
+
   ScrollContentsToOffset();
+  return true;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -210,9 +215,10 @@ void BaseScrollBar::OnGestureEvent(ui::GestureEvent* event) {
   }
 
   if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
-    ScrollByContentsOffset(IsHorizontal() ? event->details().scroll_x() :
-                                            event->details().scroll_y());
-    event->SetHandled();
+    if (ScrollByContentsOffset(IsHorizontal() ? event->details().scroll_x() :
+                                                event->details().scroll_y())) {
+      event->SetHandled();
+    }
     return;
   }
 
@@ -229,11 +235,9 @@ void BaseScrollBar::OnGestureEvent(ui::GestureEvent* event) {
 ///////////////////////////////////////////////////////////////////////////////
 // BaseScrollBar, ScrollDelegate implementation:
 
-void BaseScrollBar::OnScroll(float dx, float dy) {
-  if (IsHorizontal())
-    ScrollByContentsOffset(dx);
-  else
-    ScrollByContentsOffset(dy);
+bool BaseScrollBar::OnScroll(float dx, float dy) {
+  return IsHorizontal() ? ScrollByContentsOffset(dx) :
+                          ScrollByContentsOffset(dy);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/ui/views/controls/scrollbar/base_scroll_bar.h b/ui/views/controls/scrollbar/base_scroll_bar.h
index 4621325..94201c4 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.h
+++ b/ui/views/controls/scrollbar/base_scroll_bar.h
@@ -55,7 +55,7 @@ class VIEWS_EXPORT BaseScrollBar : public ScrollBar,
   void ScrollToThumbPosition(int thumb_position, bool scroll_to_middle);
 
   // Scroll the contents by the specified offset (contents coordinates).
-  void ScrollByContentsOffset(int contents_offset);
+  bool ScrollByContentsOffset(int contents_offset);
 
   // View overrides:
   virtual gfx::Size GetPreferredSize() OVERRIDE = 0;
@@ -77,7 +77,7 @@ class VIEWS_EXPORT BaseScrollBar : public ScrollBar,
   virtual int GetPosition() const OVERRIDE;
 
   // ScrollDelegate overrides:
-  virtual void OnScroll(float dx, float dy) OVERRIDE;
+  virtual bool OnScroll(float dx, float dy) OVERRIDE;
 
   // ContextMenuController overrides:
   virtual void ShowContextMenuForView(View* source,