cc: Fix resource eviction with impl-side painting.

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 9ee1e4201c118f7560f89e57d6d8882ee475480d..3fcfad2aca1cc855693a71a861be4f5fc610820a 100644
--- a/cc/layer_tree_host.cc
+++ b/cc/layer_tree_host.cc
@@ -254,6 +254,10 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
 {
     DCHECK(m_proxy->isImplThread());
 
+    // If there are linked evicted backings, these backings' resources may be put into the
+    // impl tree, so we can't draw yet. Determine this before clearing all evicted backings.
+    bool newImplTreeHasNoEvictedResources = !m_contentsTextureManager->linkedEvictedBackingsExist();

[enne (OOO), 2013/01/17 17:31:14]

Could you explain why this code moved from ThreadProxy to here?  I'm not sure I
follow.

[reveman, 2013/01/17 18:49:49]

We need to call ResetContentsTexturesPurged() on the syncTree which is not the
same as the activeTree. Normally it's the same but in the case of impl-side
painting the syncTree is the pendingTree.

I found moving the code here much cleaner than adding some impl-side painting
conditional code to ThreadProxy.

[enne (OOO), 2013/01/17 18:57:17]

Ah, makes perfect sense.  Thanks for the explanation.

+
     m_contentsTextureManager->updateBackingsInDrawingImplTree();
     m_contentsTextureManager->reduceMemory(hostImpl->resourceProvider());
 
@@ -300,6 +304,11 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
     hostImpl->setDebugState(m_debugState);
     hostImpl->savePaintTime(m_renderingStats.totalPaintTime);
 
+    if (newImplTreeHasNoEvictedResources) {
+        if (syncTree->ContentsTexturesPurged())
+            syncTree->ResetContentsTexturesPurged();
+    }
+
     m_commitNumber++;
 }