Revert "base: Implement browser process support for discardable memory."

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 4e8819c49cbdf9182268b6ebf187cb801be81044..184bcc6121ffa5f80987507691e0facbb2ac4b44 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -656,12 +656,8 @@ void RenderThreadImpl::Init() {
 #endif
   }
 
-  // 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());
-  }
+  base::DiscardableMemoryShmemAllocator::SetInstance(
+      ChildThreadImpl::discardable_shared_memory_manager());
 
   service_registry()->AddService<RenderFrameSetup>(
       base::Bind(CreateRenderFrameSetup));