cc: Only allow trees created at the current viewport size to draw.

cc/thread_proxy.cc

Index: cc/thread_proxy.cc
diff --git a/cc/thread_proxy.cc b/cc/thread_proxy.cc
index fe92817ea58a659061e98380f4953a1c5dd5043c..9e01ae23639a8a363726d374ab28cc7679aac4f6 100644
--- a/cc/thread_proxy.cc
+++ b/cc/thread_proxy.cc
@@ -1176,9 +1176,10 @@ void ThreadProxy::renewTreePriority()
     if (m_smoothnessTakesPriorityExpirationTime > base::TimeTicks::Now())
         priority = SMOOTHNESS_TAKES_PRIORITY;
 
-    // New content always takes priority when we have an active tree with
-    // evicted resources.
-    if (m_layerTreeHostImpl->activeTree()->ContentsTexturesPurged())
+    // New content always takes priority when we the active tree has

[enne (OOO), 2013/02/13 22:41:53]

s/we //

+    // evicted resources or invalid viewport size.

[enne (OOO), 2013/02/13 22:41:53]

s/or/or there is an invalid viewport size/

+    if (m_layerTreeHostImpl->activeTree()->ContentsTexturesPurged() ||
+        m_layerTreeHostImpl->activeTree()->ViewportSizeInvalid())
         priority = NEW_CONTENT_TAKES_PRIORITY;
 
     m_layerTreeHostImpl->setTreePriority(priority);