[Android WebView] Implement the capture picture API.

ipc/ipc_channel_proxy.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 "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/debug/trace_event.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 240 matching lines @@
 #ifdef IPC_MESSAGE_LOG_ENABLED
   if (message.type() == IPC_LOGGING_ID) {
     logger->OnReceivedLoggingMessage(message);
     return;
   }
 
   if (logger->Enabled())
     logger->OnPreDispatchMessage(message);
 #endif
 
-  listener_->OnMessageReceived(message);
+  bool handled = listener_->OnMessageReceived(message);
+
+  // Prevent non-handled synchronous messages to deadlock waiting for a reply.

[joth, 2013/01/18 01:37:08]

uber-nit: this is not strictly always going to result in deadlock, it's a
straight hang (waiting for an event that is not going to happen).

[Leandro Graciá Gil, 2013/01/18 18:53:03]

Comment removed when creating a separate private method for all the return
cases.

+  if (!handled && message.is_sync()) {

[Leandro Graciá Gil, 2013/01/18 01:31:24]

Should this also happen in other places returning in this method? (e.g. if there
is no listener)

[Leandro Graciá Gil, 2013/01/18 18:53:03]

Done.

+    Message* reply = SyncMessage::GenerateReply(&message);
+    reply->set_reply_error();
+    ipc_task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&ChannelProxy::Context::OnSendMessage,
+                 this, base::Passed(scoped_ptr<Message>(reply))));
+  }

[joth, 2013/01/18 01:37:08]

this seems pretty reasonable to me, FWIW, but I'd recommend landing it first in
its own patch? splitting the android-only parts from this common code would help
keep the two apart as they cycle through the bots.

[Leandro Graciá Gil, 2013/01/18 18:53:03]

We can if either you or John have a strong opinion on this, although I included
this in the same patch in order to make sure the trybots run the same WebView
tests that exposed the problem.

 
 #ifdef IPC_MESSAGE_LOG_ENABLED
   if (logger->Enabled())
     logger->OnPostDispatchMessage(message, channel_id_);
 #endif
 }
 
 // Called on the listener's thread
 void ChannelProxy::Context::OnDispatchConnected() {
   if (channel_connected_called_)
@@ skipping 148 matching lines @@
   Channel* channel = context_.get()->channel_.get();
   // Channel must have been created first.
   DCHECK(channel) << context_.get()->channel_id_;
   return channel->GetClientEuid(client_euid);
 }
 #endif
 
 //-----------------------------------------------------------------------------
 
 }  // namespace IPC