cc: Prevent premature activation during prefer smoothness

cc/layer_tree_host_impl.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_impl.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
@@ skipping 954 matching lines @@
     pendingTree()->UpdateDrawProperties(LayerTreeImpl::UPDATE_PENDING_TREE);
 
     TRACE_EVENT_ASYNC_STEP1("cc",
                             "PendingTree", m_pendingTree.get(), "activate",
                             "state", ValueToString(activationStateAsValue()));
 
     // It's always fine to activate to an empty tree.  Otherwise, only
     // activate once all visible resources in pending tree are ready
     // or tile manager has no work scheduled for pending tree.
     if (activeTree()->RootLayer() &&
-        !pendingTree()->AreVisibleResourcesReady() &&
-        m_tileManager->HasPendingWorkScheduled(PENDING_TREE)) {
-        TRACE_EVENT_ASYNC_STEP0("cc",
-                                "PendingTree", m_pendingTree.get(), "waiting");
-      return;
+        !pendingTree()->AreVisibleResourcesReady()) {
+        // In smoothness takes priority mode, the pending tree's priorities are
+        // ignored, so the tile manager may not have work for it even though it
+        // is simultaneously not ready to be activated.
+        if (m_tileManager->GlobalState().tree_priority ==
+            SMOOTHNESS_TAKES_PRIORITY ||
+            m_tileManager->HasPendingWorkScheduled(PENDING_TREE)) {
+            TRACE_EVENT_ASYNC_STEP0("cc",
+                                    "PendingTree",
+                                    m_pendingTree.get(),
+                                    "waiting");
+            return;
+        }
     }
 
     activatePendingTree();
 }
 
 void LayerTreeHostImpl::activatePendingTree()
 {
     CHECK(m_pendingTree);
     TRACE_EVENT_ASYNC_END0("cc", "PendingTree", m_pendingTree.get());
 
@@ skipping 767 matching lines @@
     if (m_tileManager)
         m_tileManager->SetRecordRenderingStats(m_debugState.recordRenderingStats());
 }
 
 void LayerTreeHostImpl::savePaintTime(const base::TimeDelta& totalPaintTime)
 {
     m_paintTimeCounter->SavePaintTime(totalPaintTime);
 }
 
 }  // namespace cc