Flush contexts after LayerTreeHostImpl cleanup

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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 2234 matching lines @@
   mutator_->SetClient(this);
 }
 
 void LayerTreeHostImpl::CleanUpTileManagerAndUIResources() {
   ClearUIResources();
   tile_manager_.FinishTasksAndCleanUp();
   resource_pool_ = nullptr;
   tile_task_manager_ = nullptr;
   single_thread_synchronous_task_graph_runner_ = nullptr;
   image_decode_controller_ = nullptr;
+
+  // We've potentially just freed a large number of resources on our various
+  // contexts. Flushing now helps ensure these are cleaned up quickly
+  // preventing driver cache growth. See crbug.com/643251
+  if (compositor_frame_sink_) {
+    if (auto* compositor_context = compositor_frame_sink_->context_provider())
+      compositor_context->ContextGL()->ShallowFlushCHROMIUM();
+    if (auto* worker_context =
+            compositor_frame_sink_->worker_context_provider()) {
+      ContextProvider::ScopedContextLock hold(worker_context);
+      worker_context->ContextGL()->ShallowFlushCHROMIUM();
+    }
+  }
 }
 
 void LayerTreeHostImpl::ReleaseCompositorFrameSink() {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::ReleaseCompositorFrameSink");
 
   if (!compositor_frame_sink_)
     return;
 
   // Since we will create a new resource provider, we cannot continue to use
   // the old resources (i.e. render_surfaces and texture IDs). Clear them
@@ skipping 1919 matching lines @@
   if (is_visible) {
     worker_context_visibility_ =
         worker_context->CacheController()->ClientBecameVisible();
   } else {
     worker_context->CacheController()->ClientBecameNotVisible(
         std::move(worker_context_visibility_));
   }
 }
 
 }  // namespace cc