Define a --force-gpu-rasterization flag

cc/trees/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/trees/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 1688 matching lines @@
   client_->SetNeedsRedrawOnImplThread();
 }
 
 ManagedMemoryPolicy LayerTreeHostImpl::ActualManagedMemoryPolicy() const {
   ManagedMemoryPolicy actual = cached_managed_memory_policy_;
   // TODO(ernstm): The second condition disables pre-painting for all layers
   // when GPU rasterization is enabled. Once we selectively enable GPU
   // rasterization per layer, we also need to disable pre-painting selectively:
   // crbug.com/335387
   if (debug_state_.rasterize_only_visible_content ||
-      settings_.gpu_rasterization) {
+      settings_.gpu_rasterization_state !=
+          LayerTreeSettings::GpuRasterizationDisabled) {
     actual.priority_cutoff_when_visible =
         gpu::MemoryAllocation::CUTOFF_ALLOW_REQUIRED_ONLY;
   }
 
   if (zero_budget_) {
     actual.bytes_limit_when_visible = 0;
   }
 
   return actual;
 }
@@ skipping 1313 matching lines @@
   swap_promise_monitor_.erase(monitor);
 }
 
 void LayerTreeHostImpl::NotifySwapPromiseMonitorsOfSetNeedsRedraw() {
   std::set<SwapPromiseMonitor*>::iterator it = swap_promise_monitor_.begin();
   for (; it != swap_promise_monitor_.end(); it++)
     (*it)->OnSetNeedsRedrawOnImpl();
 }
 
 }  // namespace cc