[cc] Pass on BeginFrameAcks from CompositorEBFS through RWHVAura, DFH.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 175f1687e6f05778a8a79f281bf0831e8737ec5e..f6281364fc7bb3cc94f32013a2882549e03f8728 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -553,6 +553,8 @@ bool RenderWidgetHostImpl::OnMessageReceived(const IPC::Message &msg) {
     IPC_MESSAGE_HANDLER(ViewHostMsg_SetTooltipText, OnSetTooltipText)
     IPC_MESSAGE_HANDLER_GENERIC(ViewHostMsg_SwapCompositorFrame,
                                 OnSwapCompositorFrame(msg))
+    IPC_MESSAGE_HANDLER(ViewHostMsg_BeginFrameDidNotSwap,
+                        OnBeginFrameDidNotSwap)
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateRect, OnUpdateRect)
     IPC_MESSAGE_HANDLER(ViewHostMsg_SetCursor, OnSetCursor)
     IPC_MESSAGE_HANDLER(ViewHostMsg_TextInputStateChanged,
@@ -1826,6 +1828,18 @@ bool RenderWidgetHostImpl::OnSwapCompositorFrame(
   std::vector<IPC::Message> messages_to_deliver_with_frame;
   messages_to_deliver_with_frame.swap(std::get<2>(param));
 
+  if (frame.metadata.begin_frame_ack.sequence_number <
+      cc::BeginFrameArgs::kStartingFrameNumber) {
+    // Received an invalid ack, renderer misbehaved.
+    bad_message::ReceivedBadMessage(
+        GetProcess(),
+        bad_message::RWH_INVALID_BEGIN_FRAME_ACK_COMPOSITOR_FRAME);
+    return false;
+  }
+  // |has_damage| and |remaining_frames| are not transmitted.

[dcheng, 2017/03/17 18:39:19]

Alternatively, this could just be part of the ReceivedBadMessage check on line
1831. Conceptually, that might make more sense.

+  frame.metadata.begin_frame_ack.has_damage = true;
+  frame.metadata.begin_frame_ack.remaining_frames = 0;
+
   if (!ui::LatencyInfo::Verify(frame.metadata.latency_info,
                                "RenderWidgetHostImpl::OnSwapCompositorFrame")) {
     std::vector<ui::LatencyInfo>().swap(frame.metadata.latency_info);
@@ -1869,6 +1883,24 @@ bool RenderWidgetHostImpl::OnSwapCompositorFrame(
   return true;
 }
 
+void RenderWidgetHostImpl::OnBeginFrameDidNotSwap(
+    const cc::BeginFrameAck& ack) {
+  if (ack.sequence_number < cc::BeginFrameArgs::kStartingFrameNumber) {
+    // Received an invalid ack, renderer misbehaved.
+    bad_message::ReceivedBadMessage(
+        GetProcess(), bad_message::RWH_INVALID_BEGIN_FRAME_ACK_DID_NOT_SWAP);
+    return;
+  }
+
+  // |has_damage| and |remaining_frames| are not transmitted.
+  cc::BeginFrameAck modified_ack = ack;
+  modified_ack.has_damage = false;
+  modified_ack.remaining_frames = 0;

[dcheng, 2017/03/17 18:39:19]

Ditto.

+
+  if (view_)
+    view_->OnBeginFrameDidNotSwap(modified_ack);
+}
+
 void RenderWidgetHostImpl::OnUpdateRect(
     const ViewHostMsg_UpdateRect_Params& params) {
   TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::OnUpdateRect");