Adds BeginFrameControl via DevTools.

content/browser/devtools/protocol/emulation_handler.cc

Index: content/browser/devtools/protocol/emulation_handler.cc
diff --git a/content/browser/devtools/protocol/emulation_handler.cc b/content/browser/devtools/protocol/emulation_handler.cc
index a2f4cbd8082f9f2add3bce35701c566bbb2a45e0..e8916e4208ca2e6c2ba366ced7b1c17d918e3d80 100644
--- a/content/browser/devtools/protocol/emulation_handler.cc
+++ b/content/browser/devtools/protocol/emulation_handler.cc
@@ -6,15 +6,25 @@
 
 #include <utility>
 
+#include "base/bind.h"
+#include "base/guid.h"
+#include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
+#include "cc/output/begin_frame_args.h"
+#include "cc/surfaces/surface_id_allocator.h"
+#include "cc/surfaces/surface_manager.h"
+#include "content/browser/compositor/surface_utils.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
+#include "content/browser/web_contents/web_contents_view.h"
 #include "content/common/view_messages.h"
 #include "content/public/common/url_constants.h"
 #include "device/geolocation/geolocation_service_context.h"
 #include "device/geolocation/geoposition.h"
+#include "ui/compositor/compositor.h"
 
 namespace content {
 namespace devtools {
@@ -56,10 +66,67 @@ ui::GestureProviderConfigType TouchEmulationConfigurationToType(
 
 }  // namespace
 
+class EmulatedBeginFrameSource : public cc::ExternalBeginFrameSource {
+ public:
+  explicit EmulatedBeginFrameSource(cc::ExternalBeginFrameSourceClient* client)
+      : cc::ExternalBeginFrameSource(client) {}
+  ~EmulatedBeginFrameSource() override {}
+
+  void DidFinishFrame(cc::BeginFrameObserver* obs,
+                      size_t remaining_frames) override {
+    cc::ExternalBeginFrameSource::DidFinishFrame(obs, remaining_frames);
+    finished_observers_.insert(obs);
+    CheckFinished();
+  }
+
+  void AddObserver(cc::BeginFrameObserver* obs) override {
+    cc::ExternalBeginFrameSource::AddObserver(obs);
+    sorted_observers_.insert(obs);
+  }
+
+  void RemoveObserver(cc::BeginFrameObserver* obs) override {
+    cc::ExternalBeginFrameSource::RemoveObserver(obs);
+    sorted_observers_.erase(obs);
+    finished_observers_.erase(obs);
+    CheckFinished();
+  }
+
+  void SendBeginFrame(const cc::BeginFrameArgs& args) {
+    finished_observers_.clear();
+    OnBeginFrame(args);
+
+    for (cc::BeginFrameObserver* obs : sorted_observers_) {
+      // TODO(eseckler): Need sequence numbers in args to distinguish emulated
+      // args with equal timestamps.
+      if (obs->LastUsedBeginFrameArgs().frame_time != args.frame_time)
+        finished_observers_.insert(obs);
+    }
+    CheckFinished();
+  }
+
+  void WhenFinished(base::Callback<void()> callback) { callback_ = callback; }
+
+ private:
+  void CheckFinished() {
+    if (!base::STLIncludes(finished_observers_, sorted_observers_))
+      return;
+
+    if (callback_)
+      callback_.Run();
+  }
+
+  base::Callback<void()> callback_;
+  std::set<cc::BeginFrameObserver*> sorted_observers_;
+  std::set<cc::BeginFrameObserver*> finished_observers_;
+};
+
 EmulationHandler::EmulationHandler()
     : touch_emulation_enabled_(false),
       device_emulation_enabled_(false),
-      host_(nullptr) {
+      begin_frame_source_(nullptr),
+      needs_begin_frame_(false),
+      host_(nullptr),
+      weak_factory_(this) {
 }
 
 EmulationHandler::~EmulationHandler() {
@@ -69,16 +136,23 @@ void EmulationHandler::SetRenderFrameHost(RenderFrameHostImpl* host) {
   if (host_ == host)
     return;
 
+  DisableBeginFrameControl();
+
   host_ = host;
   UpdateTouchEventEmulationState();
   UpdateDeviceEmulationState();
 }
 
+void EmulationHandler::SetClient(std::unique_ptr<Client> client) {
+  client_.swap(client);
+}
+
 void EmulationHandler::Detached() {
   touch_emulation_enabled_ = false;
   device_emulation_enabled_ = false;
   UpdateTouchEventEmulationState();
   UpdateDeviceEmulationState();
+  DisableBeginFrameControl();
 }
 
 Response EmulationHandler::SetGeolocationOverride(
@@ -290,6 +364,142 @@ Response EmulationHandler::SetVirtualTimePolicy(
   return Response::FallThrough();
 }
 
+#if defined(USE_AURA)
+Response EmulationHandler::EnableBeginFrameControl() {
+  if (begin_frame_source_)
+    return Response::OK();  // already enabled.
+
+  WebContentsImpl* web_contents = GetWebContents();
+  if (!web_contents)
+    return Response::InternalError("Could not connect to view");
+
+  ui::Compositor* compositor = web_contents->GetView()->GetCompositor();
+  if (!compositor)
+    return Response::InternalError("Could not obtain Compositor for view");
+
+  TRACE_EVENT_INSTANT2("cc", "EnableBeginFrameControl",
+                       TRACE_EVENT_SCOPE_THREAD, "WebContents RoutingID",
+                       web_contents->GetRoutingID(), "Compositor FrameSinkId",
+                       compositor->frame_sink_id().ToString());
+
+  // TODO(eseckler): Support that Display of WebContents may change (and be
+  // destroyed) while BFC is enabled.
+
+  // Replace original BeginFrameSource by our DevTools-controlled one.
+  std::unique_ptr<cc::BeginFrameSource> begin_frame_source =
+      base::MakeUnique<EmulatedBeginFrameSource>(this);
+  begin_frame_source_ =
+      static_cast<EmulatedBeginFrameSource*>(begin_frame_source.get());
+  compositor->SwapBeginFrameSource(&begin_frame_source);
+  original_begin_frame_source_.swap(begin_frame_source);
+
+  return Response::OK();
+}
+
+Response EmulationHandler::DisableBeginFrameControl() {
+  if (!begin_frame_source_)
+    return Response::OK();  // already disabled.
+
+  WebContentsImpl* web_contents = GetWebContents();
+  if (!web_contents)
+    return Response::InternalError("Could not connect to view");
+
+  ui::Compositor* compositor = web_contents->GetView()->GetCompositor();
+  DCHECK(compositor);
+
+  compositor->SwapBeginFrameSource(&original_begin_frame_source_);
+  original_begin_frame_source_.reset();
+  begin_frame_source_ = nullptr;
+  needs_begin_frame_ = false;
+  return Response::OK();
+}
+
+Response EmulationHandler::SendBeginFrame(double interval,
+                                          const double* frame_time,
+                                          const double* deadline,
+                                          std::string* out_frame_id) {
+  if (!begin_frame_source_)
+    return Response::ServerError("BeginFrameControl not enabled");
+
+  RenderWidgetHostImpl* widget_host =
+      host_ ? host_->GetRenderWidgetHost() : nullptr;
+  if (!widget_host)
+    return Response::ServerError("Target does not support SendBeginFrame");
+
+  ui::Compositor* compositor = GetWebContents()->GetView()->GetCompositor();
+  DCHECK(compositor);
+
+  base::TimeTicks frame_time_ticks =
+      frame_time
+          ? base::TimeTicks::Now()
+          : base::TimeTicks() + base::TimeDelta::FromMicroseconds(*frame_time);
+  base::TimeDelta interval_delta = base::TimeDelta::FromMicroseconds(interval);
+  base::TimeTicks deadline_ticks =
+      deadline
+          ? (base::TimeTicks() + base::TimeDelta::FromMicroseconds(*deadline))
+          : (frame_time_ticks + interval_delta);
+  auto args = cc::BeginFrameArgs::Create(
+      BEGINFRAME_FROM_HERE, frame_time_ticks, deadline_ticks, interval_delta,
+      cc::BeginFrameArgs::NORMAL);
+
+  // TODO(eseckler): Expose via DevTools?
+  // Ensure that we give the renderer main thread(s) a chance to answer this
+  // BeginFrame (disables Begin(Main)Frame skipping).
+  args.allow_latency_optimizations = false;
+
+  *out_frame_id = base::GenerateGUID();
+
+  begin_frame_source_->WhenFinished(
+      base::Bind(&EmulationHandler::ClientFrameCommitted,
+                 base::Unretained(this), *out_frame_id));
+  begin_frame_source_->SendBeginFrame(args);
+  return Response::OK();
+}
+
+#else
+Response EmulationHandler::EnableBeginFrameControl() {
+  return Response::InternalError("Only supported on Aura.");
+}
+
+Response EmulationHandler::DisableBeginFrameControl() {
+  return Response::InternalError("Only supported on Aura.");
+}
+
+Response EmulationHandler::SendBeginFrame(double interval,
+                                          const double* frame_time,
+                                          const double* deadline,
+                                          std::string* out_frame_id) {
+  return Response::InternalError("Only supported on Aura.");
+}
+#endif
+
+void EmulationHandler::OnNeedsBeginFrames(bool needs_begin_frames) {
+  if (needs_begin_frame_ == needs_begin_frames)
+    return;
+
+  needs_begin_frame_ = needs_begin_frames;
+  ClientSetNeedsBeginFrame(needs_begin_frame_);
+
+  // TODO(eseckler): Figure out if we need to capture needsBeginFrame updates
+  // elsewhere to avoid indicating (sole) presence of browser-level consumers.
+}
+
+void EmulationHandler::ClientSetNeedsBeginFrame(bool needs_begin_frame) {
+  if (!client_ || !begin_frame_source_)
+    return;
+
+  client_->SetNeedsBeginFrame(SetNeedsBeginFrameParams::Create()
+                                  ->set_needs_begin_frame(needs_begin_frame));
+}
+
+void EmulationHandler::ClientFrameCommitted(const std::string& frame_id) {
+  if (!client_ || !begin_frame_source_)
+    return;
+
+  client_->FrameCommitted(
+      FrameCommittedParams::Create()->set_frame_id(frame_id));
+}
+
 WebContentsImpl* EmulationHandler::GetWebContents() {
   return host_ ?
       static_cast<WebContentsImpl*>(WebContents::FromRenderFrameHost(host_)) :