Add glue between the client and engine for Blimp

blimp/client/compositor/blimp_compositor.h

Index: blimp/client/compositor/blimp_compositor.h
diff --git a/blimp/client/compositor/blimp_compositor.h b/blimp/client/compositor/blimp_compositor.h
index f9b319d102104f2e3814ce7d53794679504754e5..dff777ba2f98d00cccf8eea15f43dd151d8d202c 100644
--- a/blimp/client/compositor/blimp_compositor.h
+++ b/blimp/client/compositor/blimp_compositor.h
@@ -5,11 +5,16 @@
 #ifndef BLIMP_CLIENT_COMPOSITOR_BLIMP_COMPOSITOR_H_
 #define BLIMP_CLIENT_COMPOSITOR_BLIMP_COMPOSITOR_H_
 
+#include <vector>
+
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "blimp/client/blimp_client_export.h"
+#include "blimp/client/compositor/render_widget_message_processor.h"
 #include "cc/trees/layer_tree_host_client.h"
 #include "cc/trees/layer_tree_settings.h"
+#include "cc/trees/remote_proto_channel.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/native_widget_types.h"
 
@@ -24,17 +29,57 @@ class LayerTreeHost;
 
 namespace blimp {
 
+class BlimpMessage;
+
 // BlimpCompositor provides the basic framework and setup to host a
-// LayerTreeHost (compositor).  The rendering surface this compositor draws to
-// is defined by the gfx::AcceleratedWidget returned by
-// BlimpCompositor::GetWindow().
-class BlimpCompositor : public cc::LayerTreeHostClient {
+// LayerTreeHost.  The class that owns the LayerTreeHost is usually called the
+// compositor, but the LayerTreeHost does the compositing work.  The rendering
+// surface this compositor draws to is defined by the gfx::AcceleratedWidget set
+// by SetAcceleratedWidget().  This class should only be accessed from the main
+// thread.  Any interaction with the compositing thread should happen through
+// the LayerTreeHost or RemoteChannelImpl.
+class BLIMP_CLIENT_EXPORT BlimpCompositor
+    : public cc::LayerTreeHostClient,
+      public cc::RemoteProtoChannel,
+      public RenderWidgetMessageProcessor::RenderWidgetMessageDelegate {
+
  public:
   ~BlimpCompositor() override;
 
+  // Sets whether or not this compositor actually draws to the output surface.
+  // Setting this to false will make the compositor drop all of its resources
+  // and the output surface.  Setting it to true again will rebuild the output
+  // surface from the gfx::AcceleratedWidget (see SetAcceleratedWidget).
   void SetVisible(bool visible);
+
+  // Sets the size of the viewport on the compositor.
+  // TODO(dtrainor): Should this be set from the engine all the time?
   void SetSize(const gfx::Size& size);
 
+  // Lets this compositor know that it can draw to |widget|.  This means that,
+  // if this compositor is visible, it will build an output surface and GL
+  // context around |widget| and will draw to it.  ReleaseAcceleratedWidget()
+  // *must* be called before SetAcceleratedWidget() is called with the same
+  // gfx::AcceleratedWidget on another compositor.
+  void SetAcceleratedWidget(gfx::AcceleratedWidget widget);
+
+  // Releases the internally stored gfx::AcceleratedWidget and the associated
+  // output surface.  This must be called before calling
+  // SetAcceleratedWidget() with the same gfx::AcceleratedWidget on another
+  // compositor.
+  void ReleaseAcceleratedWidget();
+
+ protected:
+  // |dp_to_px| is the scale factor required to move from dp (device pixels) to
+  // px.  See https://developer.android.com/guide/practices/screens_support.html
+  // for more details.
+  explicit BlimpCompositor(float dp_to_px);
+
+  // Populates the cc::LayerTreeSettings used by the cc::LayerTreeHost.  Can be
+  // overridden to provide custom settings parameters.
+  virtual void GenerateLayerTreeSettings(cc::LayerTreeSettings* settings);
+
+ private:
   // LayerTreeHostClient implementation.
   void WillBeginMainFrame() override;
   void DidBeginMainFrame() override;
@@ -59,22 +104,21 @@ class BlimpCompositor : public cc::LayerTreeHostClient {
       scoped_ptr<cc::FrameTimingTracker::MainFrameTimingSet> main_frame_events)
       override;
 
- protected:
-  // |dp_to_px| is the scale factor required to move from dp (device pixels) to
-  // px.
-  explicit BlimpCompositor(float dp_to_px);
+  // RemoteProtoChannel implementation.
+  void SetProtoReceiver(ProtoReceiver* receiver) override;
+  void SendCompositorProto(const cc::proto::CompositorMessage& proto) override;
 
-  // Returns a widget for use in constructing this compositor's OutputSurface.
-  // Will only ever be called while this compositor is visible.
-  virtual gfx::AcceleratedWidget GetWindow() = 0;
+  // RenderWidgetMessageDelegate implementation.
+  void OnRenderWidgetInitialized() override;
+  void OnCompositorMessageReceived(
+      scoped_ptr<cc::proto::CompositorMessage> message) override;
 
-  // Populates the cc::LayerTreeSettings used by the cc::LayerTreeHost.  Can be
-  // overridden to provide custom settings parameters.
-  virtual void GenerateLayerTreeSettings(cc::LayerTreeSettings* settings);
+  // Helper method to build the internal CC compositor instance from |message|.
+  void CreateLayerTreeHost(scoped_ptr<cc::proto::CompositorMessage> message);
 
- private:
   // Creates (if necessary) and returns a TaskRunner for a thread meant to run
   // compositor rendering.
+  void HandlePendingOutputSurfaceRequest();
   scoped_refptr<base::SingleThreadTaskRunner> GetCompositorTaskRunner();
 
   gfx::Size viewport_size_;
@@ -88,6 +132,28 @@ class BlimpCompositor : public cc::LayerTreeHostClient {
   // Lazily created thread that will run the compositor rendering tasks.
   scoped_ptr<base::Thread> compositor_thread_;
 
+  gfx::AcceleratedWidget window_;
+
+  // Whether or not |host_| should be visible.  This is stored in case |host_|
+  // is null when SetVisible() is called or if we don't have a
+  // gfx::AcceleratedWidget to build an output surface from.
+  bool host_should_be_visible_;
+
+  // Whether there is an OutputSurface request pending from the current
+  // |host_|. Becomes |true| if RequestNewOutputSurface is called, and |false|
+  // if |host_| is deleted or we succeed in creating *and* initializing an
+  // OutputSurface (which is essentially the contract with cc).
+  bool output_surface_request_pending_;
+
+  // To be notified of any incoming compositor protos that are specifically sent
+  // to |render_widget_id_|.
+  cc::RemoteProtoChannel::ProtoReceiver* remote_proto_channel_receiver_;
+
+  // The bridge to the network layer that does the proto/RenderWidget id work.
+  // TODO(dtrainor): Move this to a higher level once we start dealing with
+  // multiple tabs.
+  RenderWidgetMessageProcessor render_widget_processor_;
+
   DISALLOW_COPY_AND_ASSIGN(BlimpCompositor);
 };