cc: Introduce BeginFrame sequence numbers and acknowledgements.

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index c0daedb3742ad67bd53a166e75877f14c7c4db38..cbc425e1c46e02935403ec12f3641f04cd99d74c 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -76,7 +76,6 @@
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 #include "third_party/skia/include/core/SkCanvas.h"
-#include "ui/android/delegated_frame_host_android.h"
 #include "ui/android/window_android.h"
 #include "ui/android/window_android_compositor.h"
 #include "ui/base/layout.h"
@@ -438,7 +437,7 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
     RenderWidgetHostImpl* widget_host,
     ContentViewCoreImpl* content_view_core)
     : host_(widget_host),
-      outstanding_vsync_requests_(0),
+      outstanding_begin_frame_requests_(0),
       is_showing_(!widget_host->is_hidden()),
       is_window_visible_(true),
       is_window_activity_started_(true),
@@ -461,9 +460,7 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
   view_.SetLayer(cc::Layer::Create());
   if (using_browser_compositor_) {
     delegated_frame_host_.reset(new ui::DelegatedFrameHostAndroid(
-        &view_, cached_background_color_,
-        base::Bind(&RenderWidgetHostViewAndroid::ReturnResources,
-                   weak_ptr_factory_.GetWeakPtr())));
+        &view_, cached_background_color_, this));
   }
 
   host_->SetView(this);
@@ -806,9 +803,9 @@ void RenderWidgetHostViewAndroid::SetNeedsBeginFrames(bool needs_begin_frames) {
   TRACE_EVENT1("cc", "RenderWidgetHostViewAndroid::SetNeedsBeginFrames",
                "needs_begin_frames", needs_begin_frames);
   if (needs_begin_frames)
-    RequestVSyncUpdate(PERSISTENT_BEGIN_FRAME);
+    AddBeginFrameRequest(PERSISTENT_BEGIN_FRAME);
   else
-    outstanding_vsync_requests_ &= ~PERSISTENT_BEGIN_FRAME;
+    ClearBeginFrameRequest(PERSISTENT_BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::OnStartContentIntent(
@@ -858,11 +855,11 @@ bool RenderWidgetHostViewAndroid::OnTouchEvent(
   host_->ForwardTouchEventWithLatencyInfo(web_event, latency_info);
 
   // Send a proactive BeginFrame for this vsync to reduce scroll latency for
-  // scroll-inducing touch events. Note that Android's Choreographer ensures
-  // that BeginFrame requests made during ACTION_MOVE dispatch will be honored
-  // in the same vsync phase.
+  // scroll-inducing touch events. Note that even if we weren't observing the
+  // BeginFrameSource prior to this, we will receive a (missed) BeginFrame for
+  // the current vsync phase.
   if (observing_root_window_ && result.moved_beyond_slop_region)
-    RequestVSyncUpdate(BEGIN_FRAME);
+    AddBeginFrameRequest(BEGIN_FRAME);
 
   return true;
 }
@@ -1159,7 +1156,24 @@ void RenderWidgetHostViewAndroid::DestroyDelegatedContent() {
 void RenderWidgetHostViewAndroid::OnSwapCompositorFrame(
     uint32_t compositor_frame_sink_id,
     cc::CompositorFrame frame) {
+  uint64_t begin_frame_source_id = frame.metadata.begin_frame_source_id;
+  uint64_t begin_frame_number = frame.metadata.begin_frame_number;
+  uint64_t oldest_incorporated_frame = frame.metadata.oldest_incorporated_frame;
+
   InternalSwapCompositorFrame(compositor_frame_sink_id, std::move(frame));
+
+  // DelegatedFrameHostAndroid always submits a frame.
+  bool has_updates = true;
+  cc::BeginFrameAck ack(begin_frame_source_id, begin_frame_number, has_updates,
+                        oldest_incorporated_frame, 0);
+  if (begin_frame_source_)
+    begin_frame_source_->DidFinishFrame(this, ack);
+}
+
+void RenderWidgetHostViewAndroid::OnBeginFrameDidNotDraw(
+    cc::BeginFrameAck ack) {
+  if (begin_frame_source_)
+    begin_frame_source_->DidFinishFrame(this, ack);
 }
 
 void RenderWidgetHostViewAndroid::ClearCompositorFrame() {
@@ -1390,7 +1404,7 @@ void RenderWidgetHostViewAndroid::ShowInternal() {
 
   if (content_view_core_) {
     StartObservingRootWindow();
-    RequestVSyncUpdate(BEGIN_FRAME);
+    AddBeginFrameRequest(BEGIN_FRAME);
   }
 }
 
@@ -1433,23 +1447,48 @@ void RenderWidgetHostViewAndroid::HideInternal() {
   host_->WasHidden();
 }
 
-void RenderWidgetHostViewAndroid::RequestVSyncUpdate(uint32_t requests) {
-  bool should_request_vsync = !outstanding_vsync_requests_ && requests;
-  outstanding_vsync_requests_ |= requests;
+void RenderWidgetHostViewAndroid::SetBeginFrameSource(
+    cc::BeginFrameSource* begin_frame_source) {
+  if (begin_frame_source_ == begin_frame_source)
+    return;
+
+  if (begin_frame_source_ && outstanding_begin_frame_requests_)
+    begin_frame_source_->RemoveObserver(this);
+  begin_frame_source_ = begin_frame_source;
+  if (begin_frame_source_ && outstanding_begin_frame_requests_)
+    begin_frame_source_->AddObserver(this);
+}
+
+void RenderWidgetHostViewAndroid::AddBeginFrameRequest(
+    BeginFrameRequestType request) {
+  DCHECK(this);
+  uint32_t requests = outstanding_begin_frame_requests_ | request;
 
-  // Note that if we're not currently observing the root window, outstanding
-  // vsync requests will be pushed if/when we resume observing in
-  // |StartObservingRootWindow()|.
-  if (observing_root_window_ && should_request_vsync) {
+  // Note that if we don't currently have a BeginFrameSource, outstanding begin
+  // frame requests will be pushed if/when we get one during
+  // |StartObservingRootWindow()| or when the DelegatedFrameHostAndroid sets it.
+  cc::BeginFrameSource* source = begin_frame_source_;
+  if (source && requests && !outstanding_begin_frame_requests_) {
     ui::WindowAndroid* windowAndroid = view_.GetWindowAndroid();
     DCHECK(windowAndroid);
-    // TODO(boliu): This check should be redundant with
-    // |observing_root_window_| check above. However we are receiving trickle
-    // of crash reports (crbug.com/639868) with no root cause. Should
-    // investigate more when time allows what corner case is missed.
+    // TODO(boliu): This check should be redundant with |source| check above.
+    // However, there seem to be cases where we are not notified of window
+    // destruction, which invalidates the BeginFrameSource. See also related
+    // crash reports in crbug.com/639868.
     if (windowAndroid)
-      windowAndroid->RequestVSyncUpdate();
+      source->AddObserver(this);
   }
+  outstanding_begin_frame_requests_ = requests;
+}
+
+void RenderWidgetHostViewAndroid::ClearBeginFrameRequest(
+    BeginFrameRequestType request) {
+  uint32_t requests = outstanding_begin_frame_requests_ & ~request;
+
+  cc::BeginFrameSource* source = begin_frame_source_;
+  if (source && !requests && outstanding_begin_frame_requests_)
+    source->RemoveObserver(this);
+  outstanding_begin_frame_requests_ = requests;
 }
 
 void RenderWidgetHostViewAndroid::StartObservingRootWindow() {
@@ -1465,11 +1504,9 @@ void RenderWidgetHostViewAndroid::StartObservingRootWindow() {
   if (host_)
     host_->Send(new ViewMsg_SetBeginFramePaused(host_->GetRoutingID(), false));
   view_.GetWindowAndroid()->AddObserver(this);
-
-  // Clear existing vsync requests to allow a request to the new window.
-  uint32_t outstanding_vsync_requests = outstanding_vsync_requests_;
-  outstanding_vsync_requests_ = 0;
-  RequestVSyncUpdate(outstanding_vsync_requests);
+  // When using browser compositor, DelegatedFrameHostAndroid provides the BFS.
+  if (!using_browser_compositor_)
+    SetBeginFrameSource(view_.GetWindowAndroid()->GetBeginFrameSource());
 
   ui::WindowAndroidCompositor* compositor =
       view_.GetWindowAndroid()->GetCompositor();
@@ -1480,6 +1517,8 @@ void RenderWidgetHostViewAndroid::StartObservingRootWindow() {
 }
 
 void RenderWidgetHostViewAndroid::StopObservingRootWindow() {
+  SetBeginFrameSource(nullptr);
+
   if (!(view_.GetWindowAndroid())) {
     DCHECK(!observing_root_window_);
     return;
@@ -1501,20 +1540,17 @@ void RenderWidgetHostViewAndroid::StopObservingRootWindow() {
     delegated_frame_host_->UnregisterFrameSinkHierarchy();
 }
 
-void RenderWidgetHostViewAndroid::SendBeginFrame(base::TimeTicks frame_time,
-                                                 base::TimeDelta vsync_period) {
-  TRACE_EVENT1("cc", "RenderWidgetHostViewAndroid::SendBeginFrame",
-               "frame_time_us", frame_time.ToInternalValue());
+void RenderWidgetHostViewAndroid::SendBeginFrame(cc::BeginFrameArgs args) {
+  TRACE_EVENT2("cc", "RenderWidgetHostViewAndroid::SendBeginFrame",
+               "frame_number", args.sequence_number,
+               "frame_time_us", args.frame_time.ToInternalValue());
 
   // Synchronous compositor does not use deadline-based scheduling.
   // TODO(brianderson): Replace this hardcoded deadline after Android
-  // switches to Surfaces and the Browser's commit isn't in the critcal path.
-  base::TimeTicks deadline =
-      sync_compositor_ ? base::TimeTicks() : frame_time + (vsync_period * 0.6);
-  host_->Send(new ViewMsg_BeginFrame(
-      host_->GetRoutingID(),
-      cc::BeginFrameArgs::Create(BEGINFRAME_FROM_HERE, frame_time, deadline,
-                                 vsync_period, cc::BeginFrameArgs::NORMAL)));
+  // switches to Surfaces and the Browser's commit isn't in the critical path.
+  args.deadline = sync_compositor_ ? base::TimeTicks()
+                                   : args.frame_time + (args.interval * 0.6);
+  host_->Send(new ViewMsg_BeginFrame(host_->GetRoutingID(), args));
   if (sync_compositor_)
     sync_compositor_->DidSendBeginFrame(view_.GetWindowAndroid());
 }
@@ -1628,7 +1664,7 @@ InputEventAckState RenderWidgetHostViewAndroid::FilterInputEvent(
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");
-  RequestVSyncUpdate(FLUSH_INPUT);
+  AddBeginFrameRequest(FLUSH_INPUT);
 }
 
 BrowserAccessibilityManager*
@@ -1898,31 +1934,45 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
   DCHECK(using_browser_compositor_);
   RunAckCallbacks();
   overscroll_controller_.reset();
+  SetBeginFrameSource(nullptr);
   delegated_frame_host_->UnregisterFrameSinkHierarchy();
 }
 
-void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
-                                          base::TimeDelta vsync_period) {
-  TRACE_EVENT0("cc,benchmark", "RenderWidgetHostViewAndroid::OnVSync");
+void RenderWidgetHostViewAndroid::OnBeginFrame(const cc::BeginFrameArgs& args) {
+  TRACE_EVENT0("cc,benchmark", "RenderWidgetHostViewAndroid::OnBeginFrame");

[Sami, 2016/12/06 12:41:07]

BTW if you see failing perf benchmarks when you land this, someone might be
relying on this being called "OnVSync". I didn't find any code doing that but
just thought I'd mention the possibility.

   if (!host_)
     return;
 
-  if (outstanding_vsync_requests_ & FLUSH_INPUT) {
-    outstanding_vsync_requests_ &= ~FLUSH_INPUT;
+  // In sync mode, we disregard missed frame args to ensure that
+  // SynchronousCompositorBrowserFilter::SyncStateAfterVSync will be called
+  // during an OnVSync() observer iteration.
+  if (sync_compositor_ && args.type == cc::BeginFrameArgs::MISSED)
+    return;
+
+  if (outstanding_begin_frame_requests_ & FLUSH_INPUT) {
+    ClearBeginFrameRequest(FLUSH_INPUT);
     host_->FlushInput();
   }
 
-  if (outstanding_vsync_requests_ & BEGIN_FRAME ||
-      outstanding_vsync_requests_ & PERSISTENT_BEGIN_FRAME) {
-    outstanding_vsync_requests_ &= ~BEGIN_FRAME;
-    SendBeginFrame(frame_time, vsync_period);
+  if ((outstanding_begin_frame_requests_ & BEGIN_FRAME) ||
+      (outstanding_begin_frame_requests_ & PERSISTENT_BEGIN_FRAME)) {
+    ClearBeginFrameRequest(BEGIN_FRAME);
+    SendBeginFrame(args);
   }
 
-  // This allows for SendBeginFrame and FlushInput to modify
-  // outstanding_vsync_requests.
-  uint32_t outstanding_vsync_requests = outstanding_vsync_requests_;
-  outstanding_vsync_requests_ = 0;
-  RequestVSyncUpdate(outstanding_vsync_requests);
+  last_begin_frame_args_ = args;
+}
+
+const cc::BeginFrameArgs& RenderWidgetHostViewAndroid::LastUsedBeginFrameArgs()
+    const {
+  return last_begin_frame_args_;
+}
+
+void RenderWidgetHostViewAndroid::OnBeginFrameSourcePausedChanged(bool paused) {
+  // The BeginFrameSources we listen to don't use this. For WebView, we signal
+  // the "paused" state to the RenderWidget when our window attaches/detaches,
+  // see |StartObservingRootWindow()| and |StopObservingRootWindow()|.
+  DCHECK(!paused);
 }
 
 void RenderWidgetHostViewAndroid::OnAnimate(base::TimeTicks begin_frame_time) {