Revert of Don't reset scroll position of contents on every ScrollView layout.

ui/views/controls/scroll_view.cc

 // Copyright (c) 2012 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 "ui/views/controls/scroll_view.h"
 
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "ui/events/event.h"
@@ skipping 265 matching lines @@
     FocusRing::Uninstall(this);
     focus_ring_ = nullptr;
   }
   SchedulePaint();
 }
 
 gfx::Size ScrollView::GetPreferredSize() const {
   if (!is_bounded())
     return View::GetPreferredSize();
 
-  gfx::Size size = contents_->GetPreferredSize();
+  gfx::Size size = contents()->GetPreferredSize();
   size.SetToMax(gfx::Size(size.width(), min_height_));
   size.SetToMin(gfx::Size(size.width(), max_height_));
   gfx::Insets insets = GetInsets();
   size.Enlarge(insets.width(), insets.height());
   return size;
 }
 
 int ScrollView::GetHeightForWidth(int width) const {
   if (!is_bounded())
     return View::GetHeightForWidth(width);
 
   gfx::Insets insets = GetInsets();
   width = std::max(0, width - insets.width());
-  int height = contents_->GetHeightForWidth(width) + insets.height();
+  int height = contents()->GetHeightForWidth(width) + insets.height();
   return std::min(std::max(height, min_height_), max_height_);
 }
 
 void ScrollView::Layout() {
   if (focus_ring_)
     focus_ring_->Layout();
 
   gfx::Rect available_rect = GetContentsBounds();
   if (is_bounded()) {
     int content_width = available_rect.width();
-    int content_height = contents_->GetHeightForWidth(content_width);
+    int content_height = contents()->GetHeightForWidth(content_width);
     if (content_height > height()) {
       content_width = std::max(content_width - GetScrollBarWidth(), 0);
-      content_height = contents_->GetHeightForWidth(content_width);
+      content_height = contents()->GetHeightForWidth(content_width);
     }
-    contents_->SetSize(gfx::Size(content_width, content_height));
+    if (contents()->bounds().size() != gfx::Size(content_width, content_height))
+      contents()->SetBounds(0, 0, content_width, content_height);
   }
 
   // Most views will want to auto-fit the available space. Most of them want to
   // use all available width (without overflowing) and only overflow in
   // height. Examples are HistoryView, MostVisitedView, DownloadTabView, etc.
   // Other views want to fit in both ways. An example is PrintView. To make both
   // happy, assume a vertical scrollbar but no horizontal scrollbar. To override
   // this default behavior, the inner view has to calculate the available space,
   // used ComputeScrollBarsVisibility() to use the same calculation that is done
   // here and sets its bound to fit within.
@@ skipping 454 matching lines @@
 
 VariableRowHeightScrollHelper::RowInfo
     FixedRowHeightScrollHelper::GetRowInfo(int y) {
   if (y < top_margin_)
     return RowInfo(0, top_margin_);
   return RowInfo((y - top_margin_) / row_height_ * row_height_ + top_margin_,
                  row_height_);
 }
 
 }  // namespace views