Re-land: base: Implement browser process support for discardable memory.

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 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 "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 638 matching lines @@
 
 #if defined(OS_ANDROID) || defined(OS_LINUX)
     if (!command_line.HasSwitch(
             switches::kUseNormalPriorityForTileTaskWorkerThreads)) {
       cc::TileTaskWorkerPool::SetWorkerThreadPriority(
           base::kThreadPriority_Background);
     }
 #endif
   }
 
-  base::DiscardableMemoryShmemAllocator::SetInstance(
-      ChildThreadImpl::discardable_shared_memory_manager());
+  // In single process, browser main loop set up the discardable memory
+  // allocator.
+  if (!command_line.HasSwitch(switches::kSingleProcess)) {
+    base::DiscardableMemoryShmemAllocator::SetInstance(
+        ChildThreadImpl::discardable_shared_memory_manager());
+  }
 
   service_registry()->AddService<RenderFrameSetup>(
       base::Bind(CreateRenderFrameSetup));
 
   TRACE_EVENT_END_ETW("RenderThreadImpl::Init", 0, "");
 }
 
 RenderThreadImpl::~RenderThreadImpl() {
 }
 
@@ skipping 1135 matching lines @@
 }
 
 void RenderThreadImpl::PendingRenderFrameConnect::OnConnectionError() {
   size_t erased =
       RenderThreadImpl::current()->pending_render_frame_connects_.erase(
           routing_id_);
   DCHECK_EQ(1u, erased);
 }
 
 }  // namespace content