cc: Fix resource eviction with impl-side painting.

cc/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/layer_tree_host.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
@@ skipping 236 matching lines @@
 
 // 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,
 // should be delayed until the LayerTreeHost::commitComplete, which will run
 // after the commit, but on the main thread.
 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());
 
     // In impl-side painting, synchronize to the pending tree so that it has
     // time to raster before being displayed.  If no pending tree is needed,
     // synchronization can happen directly to the active tree.
     LayerTreeImpl* syncTree;
     bool needsFullTreeSync = false;
     if (m_settings.implSidePainting) {
         // Commits should not occur while there is already a pending tree.
@@ skipping 26 matching lines @@
     syncTree->set_source_frame_number(commitNumber());
     syncTree->set_background_color(m_backgroundColor);
     syncTree->set_has_transparent_background(m_hasTransparentBackground);
 
     hostImpl->setViewportSize(layoutViewportSize(), deviceViewportSize());
     hostImpl->setDeviceScaleFactor(deviceScaleFactor());
     hostImpl->setPageScaleFactorAndLimits(m_pageScaleFactor, m_minPageScaleFactor, m_maxPageScaleFactor);
     hostImpl->setDebugState(m_debugState);
     hostImpl->savePaintTime(m_renderingStats.totalPaintTime);
 
+    if (newImplTreeHasNoEvictedResources) {
+        if (syncTree->ContentsTexturesPurged())
+            syncTree->ResetContentsTexturesPurged();
+    }
+
     m_commitNumber++;
 }
 
 void LayerTreeHost::willCommit()
 {
     m_client->willCommit();
 
     if (m_debugState.showHudInfo()) {
         if (!m_hudLayer)
             m_hudLayer = HeadsUpDisplayLayer::create();
@@ skipping 548 matching lines @@
     for (size_t childIndex = 0; childIndex < layer->children().size(); ++childIndex)
         setAnimationEventsRecursive(events, layer->children()[childIndex].get(), wallClockTime);
 }
 
 skia::RefPtr<SkPicture> LayerTreeHost::capturePicture()
 {
     return m_proxy->capturePicture();
 }
 
 }  // namespace cc