Make scroll offset type of float in cc

cc/trees/layer_tree_host_perftest.cc

 // Copyright 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 "cc/trees/layer_tree_host.h"
 
 #include <sstream>
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ skipping 213 matching lines @@
   virtual void BuildTree() OVERRIDE {
     LayerTreeHostPerfTestJsonReader::BuildTree();
     scrollable_ = layer_tree_host()->root_layer()->children()[1];
     ASSERT_TRUE(scrollable_.get());
   }
 
   virtual void Layout() OVERRIDE {
     if (TestEnded())
       return;
     static const gfx::Vector2d delta = gfx::Vector2d(0, 10);
-    scrollable_->SetScrollOffset(scrollable_->scroll_offset() + delta);
+    scrollable_->SetScrollOffset(
+        gfx::ScrollOffsetWithDelta(scrollable_->scroll_offset(), delta));
   }
 
  private:
   scoped_refptr<Layer> scrollable_;
 };
 
 TEST_F(ScrollingLayerTreePerfTest, LongScrollablePageSingleThread) {
   SetTestName("long_scrollable_page");
   ReadTestFile("long_scrollable_page");
   RunTest(false, false, false);
@@ skipping 83 matching lines @@
 TEST_F(LayerTreeHostPerfTestJsonReader, HeavyPageThreadedImplSide) {
   begin_frame_driven_drawing_ = true;
   measure_commit_cost_ = true;
   SetTestName("heavy_page");
   ReadTestFile("heavy_layer_tree");
   RunTestWithImplSidePainting();
 }
 
 }  // namespace
 }  // namespace cc