cc: Fix resource eviction with impl-side painting.

When evicting resources with impl-side painting we need wait until
the active tree is without evicted resources before we can draw.

This moves the ContentsTexturesPurged state from LTHI to the LTI
and makes LTHI::canDraw() return false when the active LTI has
ContentsTexturesPurged set. The result is no change in behavior
when we only have one tree, while with impl-side painting when
we have two trees, canDraw() will not return true until the new
tree without ContentsTexturesPurged set has been activated.

BUG=170157


Review URL: https://chromiumcodereview.appspot.com/11886091

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@177532 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 9 insertions, 0 deletions

diff --git a/cc/layer_tree_host.cc b/cc/layer_tree_host.cc
index ca49b10..62f3995 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();
+
     m_contentsTextureManager->updateBackingsInDrawingImplTree();
     m_contentsTextureManager->reduceMemory(hostImpl->resourceProvider());
 
@@ -306,6 +310,11 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
     hostImpl->setDebugState(m_debugState);
     hostImpl->savePaintTime(m_renderingStats.totalPaintTime);
 
+    if (newImplTreeHasNoEvictedResources) {
+        if (syncTree->ContentsTexturesPurged())
+            syncTree->ResetContentsTexturesPurged();
+    }
+
     m_commitNumber++;
 }