Move page scale ownership to LayerTreeImpl.

cc/layer_tree_host.cc

Index: cc/layer_tree_host.cc
diff --git a/cc/layer_tree_host.cc b/cc/layer_tree_host.cc
index 9386699d42d4b2aa84fb560332e621d5c45565aa..680a0b8a922d021966b7d0b3d05c1c7c64d55c85 100644
--- a/cc/layer_tree_host.cc
+++ b/cc/layer_tree_host.cc
@@ -299,6 +299,32 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
 
     syncTree->FindRootScrollLayer();
 
+    if (m_settings.implSidePainting) {

[danakj, 2013/01/28 20:29:03]

how about pulling out the appropriate page_scale_delta and sent_page_scale_delta
into variables based on if. Then the syncTree->set() stuff can be
non-conditional.

[aelias_OOO_until_Jul13, 2013/01/29 06:05:14]

Done.

+        DCHECK_EQ(1, syncTree->sent_page_scale_delta());
+        syncTree->SetPageScaleFactorAndLimits(m_pageScaleFactor, m_minPageScaleFactor, m_maxPageScaleFactor);
+        syncTree->SetPageScaleDelta(hostImpl->activeTree()->page_scale_delta() / hostImpl->activeTree()->sent_page_scale_delta());

[danakj, 2013/01/28 20:29:03]

Can you add a comment here similar to the scroll code to explain this is due to
the active layer doing stuff before the pending layer was created?

That said, is this still true and needed in either place now that we sync the
pending tree instead of recreating it?

[enne (OOO), 2013/01/28 21:03:46]

Yeah, this will still be needed given that we don't sync updates to the recycle
tree (i.e. the pending tree post-activation).  Maybe that assumption should
change, but that's the state of the code now.

[aelias_OOO_until_Jul13, 2013/01/29 06:05:14]

Added comment.

+    } else {
+        syncTree->SetPageScaleFactorAndLimits(m_pageScaleFactor, m_minPageScaleFactor, m_maxPageScaleFactor);
+        syncTree->SetPageScaleDelta(syncTree->page_scale_delta() / syncTree->sent_page_scale_delta());
+        syncTree->set_sent_page_scale_delta(1);
+    }
+#if 0
+    if (layer->layerTreeImpl()->settings().implSidePainting) {
+        DCHECK(layer->layerTreeImpl()->IsPendingTree());
+        LayerImpl* active_twin = layer->layerTreeImpl()->FindActiveTreeLayerById(id());
+        // Update the scroll delta from the active layer, which may have
+        // adjusted its scroll delta prior to this pending layer being created.
+        // This code is identical to that in LayerImpl::setScrollDelta.
+        if (active_twin) {
+            DCHECK(layer->sentScrollDelta().IsZero());
+            layer->setScrollDelta(active_twin->scrollDelta() - active_twin->sentScrollDelta());
+        }
+    } else {
+        layer->setScrollDelta(layer->scrollDelta() - layer->sentScrollDelta());
+        layer->setSentScrollDelta(gfx::Vector2d());
+    }
+#endif
+
     if (!m_settings.implSidePainting) {
         // If we're not in impl-side painting, the tree is immediately
         // considered active.
@@ -307,7 +333,6 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
 
     hostImpl->setViewportSize(layoutViewportSize(), deviceViewportSize());
     hostImpl->setDeviceScaleFactor(deviceScaleFactor());
-    hostImpl->setPageScaleFactorAndLimits(m_pageScaleFactor, m_minPageScaleFactor, m_maxPageScaleFactor);
     hostImpl->setDebugState(m_debugState);
     hostImpl->savePaintTime(m_renderingStats.totalPaintTime);