Only do full tree sync if tree is actually changed, otherwise just push properties

We only have to run the complete tree synchronization algorithm if the cc::Layer tree's
structure is actually changed, otherwise we can just push properties over since the
cc::LayerImpl tree structure is never changed outside of commit.

Since scroll offset updates are tied into the tree synchronization algorithm, we currently
have to do a full tree sync for scroll updates. Fixing this will speed up scroll operations
but requires a bit more work.

Speeds up cc_perftests tenTenSingleThread by 7.3%

BUG=161166


Review URL: https://chromiumcodereview.appspot.com/11316297

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170881 0039d316-1c4b-4281-b951-d872f2087c98

cc/layer.cc

@@ -116,6 +116,12 @@ void Layer::setNeedsCommit()
         m_layerTreeHost->setNeedsCommit();
 }
 
+void Layer::setNeedsFullTreeSync()
+{
+    if (m_layerTreeHost)
+        m_layerTreeHost->setNeedsFullTreeSync();
+}
+
 gfx::Rect Layer::layerRectToContentRect(const gfx::RectF& layerRect) const
 {
     gfx::RectF contentRect = gfx::ScaleRect(layerRect, contentsScaleX(), contentsScaleY());
@@ -157,7 +163,7 @@ void Layer::insertChild(scoped_refptr<Layer> child, size_t index)
     index = min(index, m_children.size());
     LayerList::iterator iter = m_children.begin();
     m_children.insert(iter + index, child);
-    setNeedsCommit();
+    setNeedsFullTreeSync();
 }
 
 void Layer::removeFromParent()
@@ -175,7 +181,7 @@ void Layer::removeChild(Layer* child)
 
         child->setParent(0);
         m_children.erase(iter);
-        setNeedsCommit();
+        setNeedsFullTreeSync();
         return;
     }
 }
@@ -302,7 +308,7 @@ void Layer::setMaskLayer(Layer* maskLayer)
         m_maskLayer->setLayerTreeHost(m_layerTreeHost);
         m_maskLayer->setIsMask(true);
     }
-    setNeedsCommit();
+    setNeedsFullTreeSync();
 }
 
 void Layer::setReplicaLayer(Layer* layer)
@@ -314,7 +320,7 @@ void Layer::setReplicaLayer(Layer* layer)
     m_replicaLayer = layer;
     if (m_replicaLayer)
         m_replicaLayer->setLayerTreeHost(m_layerTreeHost);
-    setNeedsCommit();
+    setNeedsFullTreeSync();
 }
 
 void Layer::setFilters(const WebKit::WebFilterOperations& filters)
@@ -411,7 +417,7 @@ void Layer::setScrollOffset(gfx::Vector2d scrollOffset)
     m_scrollOffset = scrollOffset;
     if (m_layerScrollClient)
         m_layerScrollClient->didScroll();
-    setNeedsCommit();
+    setNeedsFullTreeSync();
 }
 
 void Layer::setMaxScrollOffset(gfx::Vector2d maxScrollOffset)

cc/layer.h

@@ -309,6 +309,7 @@ protected:
     Layer();
 
     void setNeedsCommit();
+    void setNeedsFullTreeSync();
 
     // This flag is set when layer need repainting/updating.
     bool m_needsDisplay;

cc/layer_tree_host.cc

@@ -161,6 +161,7 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::create(LayerTreeHostClient* client, con
 LayerTreeHost::LayerTreeHost(LayerTreeHostClient* client, const LayerTreeSettings& settings)
     : m_animating(false)
     , m_needsAnimateLayers(false)
+    , m_needsFullTreeSync(true)
     , m_client(client)
     , m_commitNumber(0)
     , m_renderingStats()
@@ -310,6 +311,28 @@ void LayerTreeHost::beginCommitOnImplThread(LayerTreeHostImpl* hostImpl)
     TRACE_EVENT0("cc", "LayerTreeHost::commitTo");
 }
 
+static void pushPropertiesRecursive(Layer* layer, LayerImpl* layerImpl)
+{
+    if (!layer) {
+        DCHECK(!layerImpl);
+        return;
+    }
+
+    DCHECK_EQ(layer->id(), layerImpl->id());
+    layer->pushPropertiesTo(layerImpl);
+
+    pushPropertiesRecursive(layer->maskLayer(), layerImpl->maskLayer());
+    pushPropertiesRecursive(layer->replicaLayer(), layerImpl->replicaLayer());
+
+    const std::vector<scoped_refptr<Layer> >& children = layer->children();
+    const ScopedPtrVector<LayerImpl>& implChildren = layerImpl->children();
+    DCHECK_EQ(children.size(), implChildren.size());
+
+    for (size_t i = 0; i < children.size(); ++i) {
+        pushPropertiesRecursive(children[i].get(), implChildren[i]);
+    }
+}
+
 // This function commits the LayerTreeHost to an impl tree. When modifying
 // this function, keep in mind that the function *runs* on the impl thread! Any
 // code that is logically a main thread operation, e.g. deletion of a Layer,
@@ -322,7 +345,13 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
     m_contentsTextureManager->updateBackingsInDrawingImplTree();
     m_contentsTextureManager->reduceMemory(hostImpl->resourceProvider());
 
-    hostImpl->setRootLayer(TreeSynchronizer::synchronizeTrees(rootLayer(), hostImpl->detachLayerTree(), hostImpl));
+    if (m_needsFullTreeSync) {
+        hostImpl->setRootLayer(TreeSynchronizer::synchronizeTrees(rootLayer(), hostImpl->detachLayerTree(), hostImpl));
+    } else {
+        TRACE_EVENT0("cc", "LayerTreeHost::pushPropertiesRecursive");
+        pushPropertiesRecursive(rootLayer(), hostImpl->rootLayer());
+    }
+    m_needsFullTreeSync = false;
 
     if (m_rootLayer && m_hudLayer)
         hostImpl->setHudLayer(static_cast<HeadsUpDisplayLayerImpl*>(LayerTreeHostCommon::findLayerInSubtree(hostImpl->rootLayer(), m_hudLayer->id())));
@@ -443,6 +472,12 @@ void LayerTreeHost::setNeedsCommit()
     m_proxy->setNeedsCommit();
 }
 
+void LayerTreeHost::setNeedsFullTreeSync()
+{
+    m_needsFullTreeSync = true;
+    setNeedsCommit();
+}
+
 void LayerTreeHost::setNeedsRedraw()
 {
     m_proxy->setNeedsRedraw();
@@ -481,7 +516,7 @@ void LayerTreeHost::setRootLayer(scoped_refptr<Layer> rootLayer)
     if (m_hudLayer)
         m_hudLayer->removeFromParent();
 
-    setNeedsCommit();
+    setNeedsFullTreeSync();
 }
 
 void LayerTreeHost::setDebugState(const LayerTreeDebugState& debugState)

cc/layer_tree_host.h

@@ -184,6 +184,7 @@ public:
     void setNeedsAnimate();
     // virtual for testing
     virtual void setNeedsCommit();
+    virtual void setNeedsFullTreeSync();
     void setNeedsRedraw();
     bool commitRequested() const;
 
@@ -268,6 +269,7 @@ private:
 
     bool m_animating;
     bool m_needsAnimateLayers;
+    bool m_needsFullTreeSync;
 
     base::CancelableClosure m_prepaintCallback;
 

cc/scrollbar_layer.cc

@@ -40,6 +40,15 @@ ScrollbarLayer::~ScrollbarLayer()
 {
 }
 
+void ScrollbarLayer::setScrollLayerId(int id)
+{
+    if (id == m_scrollLayerId)
+        return;
+
+    m_scrollLayerId = id;
+    setNeedsFullTreeSync();
+}
+
 int ScrollbarLayer::maxTextureSize() {
     DCHECK(layerTreeHost());
     return layerTreeHost()->rendererCapabilities().maxTextureSize;

cc/scrollbar_layer.h

@@ -25,6 +25,9 @@ public:
 
     static scoped_refptr<ScrollbarLayer> create(scoped_ptr<WebKit::WebScrollbar>, WebKit::WebScrollbarThemePainter, scoped_ptr<WebKit::WebScrollbarThemeGeometry>, int scrollLayerId);
 
+    int scrollLayerId() const { return m_scrollLayerId; }
+    void setScrollLayerId(int id);
+
     // Layer interface
     virtual void setTexturePriorities(const PriorityCalculator&) OVERRIDE;
     virtual void update(ResourceUpdateQueue&, const OcclusionTracker*, RenderingStats&) OVERRIDE;
@@ -32,9 +35,6 @@ public:
     virtual void pushPropertiesTo(LayerImpl*) OVERRIDE;
     virtual void setContentsScale(float contentsScale) OVERRIDE;
 
-    int scrollLayerId() const { return m_scrollLayerId; }
-    void setScrollLayerId(int id) { m_scrollLayerId = id; }
-
     virtual ScrollbarLayer* toScrollbarLayer() OVERRIDE;
 
 protected:

cc/tree_synchronizer.cc

@@ -4,6 +4,7 @@
 
 #include "cc/tree_synchronizer.h"
 
+#include "base/debug/trace_event.h"
 #include "cc/layer.h"
 #include "cc/layer_impl.h"
 #include "cc/scrollbar_animation_controller.h"
@@ -14,6 +15,7 @@ namespace cc {
 
 scoped_ptr<LayerImpl> TreeSynchronizer::synchronizeTrees(Layer* layerRoot, scoped_ptr<LayerImpl> oldLayerImplRoot, LayerTreeHostImpl* hostImpl)
 {
+    TRACE_EVENT0("cc", "TreeSynchronizer::synchronizeTrees");
     ScopedPtrLayerImplMap oldLayers;
     RawPtrLayerImplMap newLayers;