Add glue between the client and engine for Blimp

blimp/client/render_widget_message_processor.h

Index: blimp/client/render_widget_message_processor.h
diff --git a/blimp/client/render_widget_message_processor.h b/blimp/client/render_widget_message_processor.h
new file mode 100644
index 0000000000000000000000000000000000000000..b7cdf1f5ce4b82baff61e01b05a13ad7c5b8a3e4
--- /dev/null
+++ b/blimp/client/render_widget_message_processor.h
@@ -0,0 +1,90 @@
+// Copyright 2015 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.
+
+#ifndef BLIMP_CLIENT_RENDER_WIDGET_MESSAGE_PROCESSOR_H_

[nyquist, 2015/11/24 08:55:43]

Would it make sense to put these in some subfolder? renderwidget?
It seems a bit odd that this class is so important it has to live alone in the
top-level client-directory. Is it just because we have no browser/renderer parts
on the client?

[David Trainor- moved to gerrit, 2015/11/25 17:56:42]

Put these in compositor, as that's where they're actually used.  I'll look into
splitting it out a bit more in the future.

+#define BLIMP_CLIENT_RENDER_WIDGET_MESSAGE_PROCESSOR_H_
+
+#include "base/containers/small_map.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "blimp/client/blimp_client_export.h"
+#include "blimp/net/blimp_message_processor.h"
+#include "blimp/net/input_message_generator.h"
+
+namespace blink {
+class WebInputEvent;
+}

[nyquist, 2015/11/24 08:55:43]

Nit: // namespace blink?

[David Trainor- moved to gerrit, 2015/11/25 17:56:42]

I was explicitly asked not to for short namespace {} that just forward declared
things in a cc change.  I'm not sure if that's a general guideline or just a cc/
one though.

+
+namespace cc {
+namespace proto {
+class CompositorMessage;
+}

[nyquist, 2015/11/24 08:55:43]

Nit: end of namespace comment here and below?

[David Trainor- moved to gerrit, 2015/11/25 17:56:42]

See above.

+}
+
+namespace blimp {
+
+// Handles all incoming and outgoing protobuf message types tied to a specific
+// RenderWidget. This includes BlimpMessage::INPUT, BlimpMessage::COMPOSITOR,
+// and BlimpMessage::RENDER_WIDGET messages.  Delegates can be added to be
+// notified of incoming messages. This class automatically attaches a specific
+// id so that the engine can drop stale RenderWidget related messages after it
+// sends a RenderWidgetMessage::INITIALIZE message.
+class BLIMP_CLIENT_EXPORT RenderWidgetMessageProcessor
+    : public BlimpMessageProcessor {
+ public:
+  // A delegate to be notified of specific RenderWidget related incoming events.
+  class RenderWidgetMessageDelegate {
+   public:
+    // Called when the engine's RenderWidget has changed for a particular
+    // WebContents.  When this is received all state related to the existing
+    // client RenderWidget should be reset.
+    virtual void OnRenderWidgetInitialized() = 0;
+
+    // Called when the engine sent a CompositorMessage.  These messages should
+    // be sent to the client's RemoteChannel of the compositor.
+    virtual void OnCompositorMessageReceived(
+        scoped_ptr<cc::proto::CompositorMessage> message) = 0;
+  };
+
+  RenderWidgetMessageProcessor(
+      BlimpMessageProcessor* outgoing_message_processor);
+  ~RenderWidgetMessageProcessor() override;
+
+  // Sends a WebInputEvent for |tab_id| to the engine.
+  void SendInputEvent(const int tab_id, const blink::WebInputEvent& event);
+
+  // Sends a CompositorMessage for |tab_id| to the engine.
+  void SendCompositorMessage(const int tab_id,
+                             const cc::proto::CompositorMessage& message);
+
+  // Sets a RenderWidgetMessageDelegate to be notified of all incoming
+  // RenderWidget related messages for |tab_id| from the engine.
+  void SetDelegate(const int tab_id, RenderWidgetMessageDelegate* delegate);

[nyquist, 2015/11/24 08:55:43]

Nit: Could you add a comment saying there can only be one RWMD per |tab_id|?

[David Trainor- moved to gerrit, 2015/11/25 17:56:42]

Done.

+  void RemoveDelegate(const int tab_id);
+
+  // BlimpMessageProcessor implementation.
+  void ProcessMessage(scoped_ptr<BlimpMessage> message,
+                      const net::CompletionCallback& callback) override;
+
+ private:
+  RenderWidgetMessageDelegate* FindDelegate(const int tab_id);

[nyquist, 2015/11/24 08:55:43]

Optional nit: Do we want to add a comment saying that nullptr will be returned
if it is not found? Or is that implicit since it's a pointer you return?

[David Trainor- moved to gerrit, 2015/11/25 17:56:42]

I assumed it was implicit.  I can add a comment though.

+  uint32_t GetRenderWidgetId(const int tab_id);
+
+  typedef base::SmallMap<std::map<int, RenderWidgetMessageDelegate*> >
+      DelegateMap;
+  typedef base::SmallMap<std::map<int, uint32_t> > RenderWidgetIdMap;
+
+  DelegateMap delegates_;
+  RenderWidgetIdMap render_widget_ids_;
+
+  InputMessageGenerator input_message_generator_;
+
+  BlimpMessageProcessor* outgoing_message_processor_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderWidgetMessageProcessor);
+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_RENDER_WIDGET_MESSAGE_PROCESSOR_H_