Add a dcheck to warn if someone sends a sync IPC through IPC::ChannelProxy.

Change-Id: Ib6ee2044f8d553bb4e96feab509e0e987976665e
Reviewed-on: https://chromium-review.googlesource.com/575911Reviewed-by: Yuzhu Shen <yzshen@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487568}

ipc/ipc_channel_proxy.cc

@@ -517,6 +517,12 @@ void ChannelProxy::Close() {
 }
 
 bool ChannelProxy::Send(Message* message) {
+  DCHECK(!message->is_sync()) << "Need to use IPC::SyncChannel";
+  SendInternal(message);
+  return true;
+}
+
+void ChannelProxy::SendInternal(Message* message) {
   DCHECK(did_init_);
 
   // TODO(alexeypa): add DCHECK(CalledOnValidThread()) here. Currently there are
@@ -535,7 +541,6 @@ bool ChannelProxy::Send(Message* message) {
 #endif
 
   context_->Send(message);
-  return true;
 }
 
 void ChannelProxy::AddFilter(MessageFilter* filter) {

ipc/ipc_channel_proxy.h

@@ -377,9 +377,11 @@ class IPC_EXPORT ChannelProxy : public Sender {
   }
 #endif
 
- protected:
   bool did_init() const { return did_init_; }
 
+  // A Send() which doesn't DCHECK if the message is synchronous.
+  void SendInternal(Message* message);
+
  private:
   friend class IpcSecurityTestUtil;
 

ipc/ipc_sync_channel.cc

@@ -599,7 +599,7 @@ bool SyncChannel::Send(Message* message) {
                "line", IPC_MESSAGE_ID_LINE(message->type()));
 #endif
   if (!message->is_sync()) {
-    ChannelProxy::Send(message);
+    ChannelProxy::SendInternal(message);
     return true;
   }
 
@@ -614,7 +614,7 @@ bool SyncChannel::Send(Message* message) {
     return false;
   }
 
-  ChannelProxy::Send(message);
+  ChannelProxy::SendInternal(message);
 
   // Wait for reply, or for any other incoming synchronous messages.
   // |this| might get deleted, so only call static functions at this point.