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

content/browser/renderer_host/render_widget_host_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/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 
 #include <set>
 #include <tuple>
@@ skipping 535 matching lines @@
                         OnQueueSyntheticGesture)
     IPC_MESSAGE_HANDLER(InputHostMsg_ImeCancelComposition,
                         OnImeCancelComposition)
     IPC_MESSAGE_HANDLER(ViewHostMsg_Close, OnClose)
     IPC_MESSAGE_HANDLER(ViewHostMsg_UpdateScreenRects_ACK,
                         OnUpdateScreenRectsAck)
     IPC_MESSAGE_HANDLER(ViewHostMsg_RequestMove, OnRequestMove)
     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,
                         OnTextInputStateChanged)
     IPC_MESSAGE_HANDLER(ViewHostMsg_LockMouse, OnLockMouse)
     IPC_MESSAGE_HANDLER(ViewHostMsg_UnlockMouse, OnUnlockMouse)
     IPC_MESSAGE_HANDLER(ViewHostMsg_ShowDisambiguationPopup,
                         OnShowDisambiguationPopup)
     IPC_MESSAGE_HANDLER(ViewHostMsg_SelectionBoundsChanged,
                         OnSelectionBoundsChanged)
@@ skipping 1253 matching lines @@
   TRACE_EVENT0("test_fps,benchmark", "OnSwapCompositorFrame");
 
   ViewHostMsg_SwapCompositorFrame::Param param;
   if (!ViewHostMsg_SwapCompositorFrame::Read(&message, &param))
     return false;
   cc::CompositorFrame frame(std::move(std::get<1>(param)));
   uint32_t compositor_frame_sink_id = std::get<0>(param);
   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);
   }
 
   latency_tracker_.OnSwapCompositorFrame(&frame.metadata.latency_info);
 
   bool is_mobile_optimized = IsMobileOptimizedFrame(frame.metadata);
   input_router_->NotifySiteIsMobileOptimized(is_mobile_optimized);
   if (touch_emulator_)
@@ skipping 23 matching lines @@
        ++i) {
     rph->OnMessageReceived(*i);
     if (i->dispatch_error())
       rph->OnBadMessageReceived(*i);
   }
   messages_to_deliver_with_frame.clear();
 
   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");
   TimeTicks paint_start = TimeTicks::Now();
 
   // Update our knowledge of the RenderWidget's size.
   current_size_ = params.view_size;
 
   bool is_resize_ack =
       ViewHostMsg_UpdateRect_Flags::is_resize_ack(params.flags);
@@ skipping 677 matching lines @@
     // different from the receiver's.
     file_system_file.url =
         GURL(storage::GetIsolatedFileSystemRootURIString(
                  file_system_url.origin(), filesystem_id, std::string())
                  .append(register_name));
     file_system_file.filesystem_id = filesystem_id;
   }
 }
 
 }  // namespace content