Forward input tasks to the Blink scheduler

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 acafe552a838d58482e50bb918c03fda92b0a55d..541397496837435e8516ae3fb341d9a3ef7beb6a 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -20,6 +20,7 @@
 #include "base/metrics/histogram.h"
 #include "base/metrics/stats_table.h"
 #include "base/path_service.h"
+#include "base/single_thread_task_runner.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_tokenizer.h"
@@ -107,7 +108,10 @@
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "skia/ext/event_tracer_impl.h"
+#include "third_party/WebKit/public/platform/WebSchedulerProxy.h"
 #include "third_party/WebKit/public/platform/WebString.h"
+#include "third_party/WebKit/public/platform/WebThread.h"
+#include "third_party/WebKit/public/platform/WebTraceLocation.h"
 #include "third_party/WebKit/public/web/WebColorName.h"
 #include "third_party/WebKit/public/web/WebDatabase.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
@@ -291,6 +295,59 @@ void CreateRenderFrameSetup(mojo::InterfaceRequest<RenderFrameSetup> request) {
   mojo::BindToRequest(new RenderFrameSetupImpl(), &request);
 }
 
+// Helper for forwarding posted tasks into different WebSchedulerProxy queues.
+template <void (blink::WebSchedulerProxy::*ProxyFunction)(
+    const blink::WebTraceLocation&,
+    blink::WebThread::Task*)>
+class SchedulerProxyTaskRunner : public base::SingleThreadTaskRunner {
+ public:
+  SchedulerProxyTaskRunner()
+      : scheduler_proxy_(blink::WebSchedulerProxy::create()),
+        main_thread_id_(base::PlatformThread::CurrentId()) {}
+
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const base::Closure& task,
+                               base::TimeDelta delay) OVERRIDE {
+    DCHECK(delay == base::TimeDelta());
+    blink::WebTraceLocation location(from_here.function_name(),
+                                     from_here.file_name());
+    (scheduler_proxy_.*ProxyFunction)(location, new TaskAdapter(task));

[jamesr, 2014/07/22 01:07:23]

hm, so another malloc/free pair for every task we post in the render process?

[Sami, 2014/07/22 16:24:33]

Yeah :( Both of these are a consequence of the fact that there's no such thing
as WebClosure that we could just hand to the scheduler. I'm guessing it's not
okay to add a dependency to base/callback.h into public/web to fix this?

+    return true;
+  }
+
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const base::Closure& task,
+      base::TimeDelta delay) OVERRIDE {
+    NOTREACHED();
+    return false;
+  }
+
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE {
+    return base::PlatformThread::CurrentId() == main_thread_id_;
+  }
+
+ protected:
+  virtual ~SchedulerProxyTaskRunner() {}
+
+ private:
+  class TaskAdapter : public blink::WebThread::Task {
+   public:
+    explicit TaskAdapter(const base::Closure& function) : function_(function) {}
+    virtual ~TaskAdapter() {}
+
+    virtual void run() OVERRIDE { function_.Run(); }

[jamesr, 2014/07/22 01:07:23]

and an extra closure wrapper. hmmm

+
+   private:
+    base::Closure function_;
+  };
+
+  blink::WebSchedulerProxy scheduler_proxy_;
+  const base::PlatformThreadId main_thread_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(SchedulerProxyTaskRunner);
+};
+
 }  // namespace
 
 // For measuring memory usage after each task. Behind a command line flag.
@@ -809,6 +866,11 @@ void RenderThreadImpl::EnsureWebKitInitialized() {
 
   webkit_platform_support_.reset(new RendererWebKitPlatformSupportImpl);
   blink::initialize(webkit_platform_support_.get());
+  main_thread_compositor_task_runner_ =
+      make_scoped_refptr(new SchedulerProxyTaskRunner<
+          &blink::WebSchedulerProxy::postCompositorTask>());
+  main_thread_input_task_runner_ = make_scoped_refptr(
+      new SchedulerProxyTaskRunner<&blink::WebSchedulerProxy::postInputTask>());
 
   v8::Isolate* isolate = blink::mainThreadIsolate();
 
@@ -848,8 +910,8 @@ void RenderThreadImpl::EnsureWebKitInitialized() {
     }
 #endif
     if (!input_handler_manager_client) {
-      input_event_filter_ =
-          new InputEventFilter(this, compositor_message_loop_proxy_);
+      input_event_filter_ = new InputEventFilter(
+          this, main_thread_input_task_runner_, compositor_message_loop_proxy_);
       AddFilter(input_event_filter_.get());
       input_handler_manager_client = input_event_filter_.get();
     }