Make scroll offset type of float in cc

cc/trees/layer_tree_host.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 "cc/trees/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 1048 matching lines @@
   ScopedPtrVector<SwapPromise>::iterator it = info->swap_promises.begin();
   for (; it != info->swap_promises.end(); ++it) {
     scoped_ptr<SwapPromise> swap_promise(info->swap_promises.take(it));
     TRACE_EVENT_FLOW_STEP0("input",
                            "LatencyInfo.Flow",
                            TRACE_ID_DONT_MANGLE(swap_promise->TraceId()),
                            "Main thread scroll update");
     QueueSwapPromise(swap_promise.Pass());
   }
 
-  gfx::Vector2d inner_viewport_scroll_delta;
-  gfx::Vector2d outer_viewport_scroll_delta;
+  gfx::ScrollOffset inner_viewport_scroll_delta;

[danakj, 2014/09/25 15:13:31]

these are deltas (relative to an offset) not an offset (relative to origin) from
the name, so why the change?

[Yufeng Shen (Slow to review), 2014/09/25 20:06:24]

Done.

+  gfx::ScrollOffset outer_viewport_scroll_delta;
 
   for (size_t i = 0; i < info->scrolls.size(); ++i) {
     Layer* layer = LayerTreeHostCommon::FindLayerInSubtree(
         root_layer_.get(), info->scrolls[i].layer_id);
     if (!layer)
       continue;
     if (layer == outer_viewport_scroll_layer_.get()) {
       outer_viewport_scroll_delta += info->scrolls[i].scroll_delta;
     } else if (layer == inner_viewport_scroll_layer_.get()) {
       inner_viewport_scroll_delta += info->scrolls[i].scroll_delta;
@@ skipping 18 matching lines @@
     inner_viewport_scroll_layer_->SetScrollOffsetFromImplSide(
         inner_viewport_scroll_layer_->scroll_offset() +
         inner_viewport_scroll_delta);
     if (outer_viewport_scroll_layer_.get()) {
       outer_viewport_scroll_layer_->SetScrollOffsetFromImplSide(
           outer_viewport_scroll_layer_->scroll_offset() +
           outer_viewport_scroll_delta);
     }
     ApplyPageScaleDeltaFromImplSide(info->page_scale_delta);
 
-    client_->ApplyViewportDeltas(
-        inner_viewport_scroll_delta + outer_viewport_scroll_delta,
-        info->page_scale_delta,
-        info->top_controls_delta);
+    // TODO(miletus): Make viewport delta ScrollOffset.

[danakj, 2014/09/25 15:13:31]

Do you think all deltas should be ScrollOffset type?

[Yufeng Shen (Slow to review), 2014/09/25 20:06:24]

delta changed to be vector2dF to be consistent.

+    gfx::Vector2d viewport_scroll_delta = gfx::ToFlooredVector2d(
+        inner_viewport_scroll_delta + outer_viewport_scroll_delta);
+
+    client_->ApplyViewportDeltas(viewport_scroll_delta,
+                                 info->page_scale_delta,
+                                 info->top_controls_delta);
   }
 }
 
 void LayerTreeHost::StartRateLimiter() {
   if (inside_begin_main_frame_)
     return;
 
   if (!rate_limit_timer_.IsRunning()) {
     rate_limit_timer_.Start(FROM_HERE,
                             base::TimeDelta(),
@@ skipping 194 matching lines @@
   swap_promise_list_.push_back(swap_promise.Pass());
 }
 
 void LayerTreeHost::BreakSwapPromises(SwapPromise::DidNotSwapReason reason) {
   for (size_t i = 0; i < swap_promise_list_.size(); i++)
     swap_promise_list_[i]->DidNotSwap(reason);
   swap_promise_list_.clear();
 }
 
 }  // namespace cc