[Not for review] Discardable memory emulation

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 100 matching lines @@
 #endif
 
 #if defined(OS_POSIX)
 #include "ipc/ipc_channel_posix.h"
 #endif
 
 #if defined(ENABLE_WEBRTC)
 #include "third_party/webrtc/system_wrappers/interface/event_tracer.h"
 #endif
 
+#if !defined(OS_ANDROID) && !defined(OS_MACOSX)
+#include "base/memory/discardable_memory.h"
+#include "content/renderer/render_process_discardable_memory_provider.h"
+#include "content/renderer/render_process_visibility_manager.h"
+#endif
+
 using base::ThreadRestrictions;
 using WebKit::WebDocument;
 using WebKit::WebFrame;
 using WebKit::WebNetworkStateNotifier;
 using WebKit::WebRuntimeFeatures;
 using WebKit::WebScriptController;
 using WebKit::WebSecurityPolicy;
 using WebKit::WebString;
 using WebKit::WebView;
 
@@ skipping 266 matching lines @@
 
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kEnableGpuBenchmarking))
       RegisterExtension(GpuBenchmarkingExtension::Get());
 
 #if defined(USE_TCMALLOC) && (defined(OS_LINUX) || defined(OS_ANDROID))
   if (command_line.HasSwitch(switches::kEnableMemoryBenchmarking))
     RegisterExtension(MemoryBenchmarkingExtension::Get());
 #endif  // USE_TCMALLOC
 
+#if !defined(OS_ANDROID) && !defined(OS_MACOSX)
+  discardable_provider_.reset(new RenderProcessDiscardableMemoryProvider);
+  RenderProcessVisibilityManager::GetInstance()->AddObserver(
+      discardable_provider_.get());

[jonathan.backer, 2013/05/29 14:02:54]

I don't see the advantage of a singleton here.  RenderProcessVisibilityManager
is only referenced from inside RenderThreadImpl. Maybe RenderThreadImpl can own
it.

Right now, there is a bit of a life-time issue with the Manager and Provider. I
think that you're leaking both (which is fine). But if Manager is no longer a
singleton, you'll want to tighten this up.

Maybe Manager owns Provider/is a Provider?

+  base::DiscardableMemory::SetProvider(discardable_provider_.get());

[jonathan.backer, 2013/05/29 14:02:54]

I suspect that you may have many RenderThreadImpls per render process (multiple
tabs per process). In which case you'll have to rework SetProvider.

+#endif
+
   if (command_line.HasSwitch(switches::kEnableSkiaBenchmarking)) {
     LOG(WARNING) << "Enabling unsafe Skia benchmarking extension.";
     RegisterExtension(SkiaBenchmarkingExtension::Get());
   }
 
   context_lost_cb_.reset(new GpuVDAContextLostCallback());
 
   // Note that under Linux, the media library will normally already have
   // been initialized by the Zygote before this instance became a Renderer.
   base::FilePath media_path;
@@ skipping 197 matching lines @@
 
 void RenderThreadImpl::SetResourceDispatcherDelegate(
     ResourceDispatcherDelegate* delegate) {
   resource_dispatcher()->set_delegate(delegate);
 }
 
 void RenderThreadImpl::WidgetHidden() {
   DCHECK(hidden_widget_count_ < widget_count_);
   hidden_widget_count_++;
 
+#if !defined(OS_ANDROID) && !defined(OS_MACOSX)
+  RenderProcessVisibilityManager::GetInstance()->WidgetVisibilityChanged(false);
+#endif
+
   if (!GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
     return;
   }
 
   if (widget_count_ && hidden_widget_count_ == widget_count_)
     ScheduleIdleHandler(kInitialIdleHandlerDelayMs);
 }
 
 void RenderThreadImpl::WidgetRestored() {
   DCHECK_GT(hidden_widget_count_, 0);
   hidden_widget_count_--;
+
+#if !defined(OS_ANDROID) && !defined(OS_MACOSX)
+  RenderProcessVisibilityManager::GetInstance()->WidgetVisibilityChanged(true);
+#endif
+
   if (!GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
     return;
   }
 
   ScheduleIdleHandler(kLongIdleHandlerDelayMs);
 }
 
 static void AdjustRuntimeFeatureDefaultsForPlatform() {
 #if defined(OS_ANDROID) && !defined(GOOGLE_TV)
   WebRuntimeFeatures::enableWebKitMediaSource(false);
@@ skipping 685 matching lines @@
 
 void RenderThreadImpl::SetFlingCurveParameters(
     const std::vector<float>& new_touchpad,
     const std::vector<float>& new_touchscreen) {
   webkit_platform_support_->SetFlingCurveParameters(new_touchpad,
                                                     new_touchscreen);
 
 }
 
 }  // namespace content