ui: Prefer +/- operators to apply offsets.

cc/layer_tree_host_impl.cc

 // 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.
 
 #include "config.h"
 
 #include "cc/layer_tree_host_impl.h"
 
 #include <algorithm>
 
@@ skipping 84 matching lines @@
     m_maxPageScaleFactor = maxPageScaleFactor;
 
     m_pageScaleFactor = pageScaleFactor;
     return true;
 }
 
 gfx::RectF PinchZoomViewport::bounds() const
 {
     gfx::RectF bounds(gfx::PointF(), m_layoutViewportSize);
     bounds.Scale(1 / totalPageScaleFactor());
-    bounds.Offset(m_pinchViewportScrollDelta);
+    bounds += m_pinchViewportScrollDelta;
     return bounds;
 }
 
 gfx::Vector2dF PinchZoomViewport::applyScroll(const gfx::Vector2dF& delta)
 {
     gfx::Vector2dF overflow;
-    gfx::RectF pinchedBounds = bounds();
+    gfx::RectF pinchedBounds = bounds() + delta;
 
-    pinchedBounds.Offset(delta);
     if (pinchedBounds.x() < 0) {
         overflow.set_x(pinchedBounds.x());
         pinchedBounds.set_x(0);
     }
 
     if (pinchedBounds.y() < 0) {
         overflow.set_y(pinchedBounds.y());
         pinchedBounds.set_y(0);
     }
 
     if (pinchedBounds.right() > m_layoutViewportSize.width()) {
         overflow.set_x(pinchedBounds.right() - m_layoutViewportSize.width());
-        pinchedBounds.Offset(m_layoutViewportSize.width() - pinchedBounds.right(), 0);
+        pinchedBounds += gfx::Vector2d(m_layoutViewportSize.width() - pinchedBounds.right(), 0);
     }
 
     if (pinchedBounds.bottom() > m_layoutViewportSize.height()) {
         overflow.set_y(pinchedBounds.bottom() - m_layoutViewportSize.height());
-        pinchedBounds.Offset(0, m_layoutViewportSize.height() - pinchedBounds.bottom());
+        pinchedBounds += gfx::Vector2d(0, m_layoutViewportSize.height() - pinchedBounds.bottom());
     }
     m_pinchViewportScrollDelta = pinchedBounds.OffsetFromOrigin();
 
     return overflow;
 }
 
 WebTransformationMatrix PinchZoomViewport::implTransform() const
 {
     WebTransformationMatrix transform;
     transform.scale(m_pageScaleDelta);
@@ skipping 1341 matching lines @@
     ScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     double monotonicTime = (time - base::TimeTicks()).InSecondsF();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i], time);
 }
 
 }  // namespace cc