GLRenderer should regularly call ResourcePool::CheckBusyResources.

cc/resources/resource_pool.h

Index: cc/resources/resource_pool.h
diff --git a/cc/resources/resource_pool.h b/cc/resources/resource_pool.h
index cd11c45b21747138d9a8e4822e9a0f2dd4af997d..a2e5e2a02db2e679fb0516708d0a93b904ad10fc 100644
--- a/cc/resources/resource_pool.h
+++ b/cc/resources/resource_pool.h
@@ -64,6 +64,9 @@ class CC_EXPORT ResourcePool : public base::trace_event::MemoryDumpProvider {
                               size_t max_resource_count);
 
   void ReduceResourceUsage();
+
+  // Must be called regularly to move resources from the busy pool to the unused
+  // pool.
   void CheckBusyResources();
 
   size_t memory_usage_bytes() const { return in_use_memory_usage_bytes_; }