ozone: Add overlay candidate implementation that queries support via IPC

ui/ozone/platform/drm/host/drm_host_overlay_candidates.h

+// 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 UI_OZONE_PLATFORM_DRM_HOST_OVERLAY_CANDIDATES_H_
+#define UI_OZONE_PLATFORM_DRM_HOST_OVERLAY_CANDIDATES_H_
+
+#include <deque>
+#include <map>
+#include <vector>
+
+#include "ui/ozone/common/gpu/ozone_gpu_message_params.h"
+#include "ui/ozone/public/gpu_platform_support_host.h"
+#include "ui/ozone/public/overlay_candidates_ozone.h"
+
+namespace ui {
+
+class DrmGpuPlatformSupportHost;
+
+// This is an implementation of OverlayCandidatesOzone where the driver is asked
+// about overlay capabilities via IPC. We have no way of querying abstract
+// capabilities, only if a particular configuration is supported or not.
+// Each time we we are asked if a particular configuration is supported, if we
+// have not seen that configuration before, it is IPCed to the GPU via
+// OzoneGpuMsg_CheckOverlayCapabilities; a test commit is then performed and
+// the result is returned in OzoneHostMsg_OverlayCapabilitiesReceived. Testing
+// is asynchronous, until the reply arrives that configuration will be failed.
+//
+// There is a many:1 relationship between this class and
+// DrmGpuPlatformSupportHost, each compositor will own one of these objects.
+// Each request has a unique request ID, which is assigned from a shared
+// sequence number so that replies can be routed to the correct object.
+class DrmHostOverlayCandidates : public OverlayCandidatesOzone,

[dnicoara, 2015/05/29 19:28:23]

We should name this DrmOverlayCandidatesHost for consistency.

[achaulk, 2015/06/01 20:43:08]

Done.

+                                 public GpuPlatformSupportHost {
+  struct OverlayCompare {
+    bool operator()(const OverlayCheck_Params& l, const OverlayCheck_Params& r);
+  };
+
+ public:
+  DrmHostOverlayCandidates(gfx::AcceleratedWidget widget,
+                           DrmGpuPlatformSupportHost* platform_support);
+  ~DrmHostOverlayCandidates() override;
+
+  // OverlayCandidatesOzone:
+  void CheckOverlaySupport(OverlaySurfaceCandidateList* candidates) override;
+
+  // GpuPlatformSupportHost:
+  void OnChannelEstablished(
+      int host_id,
+      scoped_refptr<base::SingleThreadTaskRunner> send_runner,
+      const base::Callback<void(IPC::Message*)>& sender) override;
+  void OnChannelDestroyed(int host_id) override;
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+ private:
+  void SendRequest(const OverlaySurfaceCandidateList& candidates,
+                   const OverlayCheck_Params& check);
+  void OnOverlayResult(bool* handled,
+                       gfx::AcceleratedWidget widget,
+                       bool result);
+  void ProcessResult(const OverlayCheck_Params& check, bool result);
+
+  void CheckSingleOverlay(OverlaySurfaceCandidateList* candidates);
+
+  gfx::AcceleratedWidget widget_;
+  DrmGpuPlatformSupportHost* platform_support_;  // Not owned.
+
+  std::deque<OverlayCheck_Params> pending_checks_;
+  std::map<OverlayCheck_Params, bool, OverlayCompare> cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(DrmHostOverlayCandidates);
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PLATFORM_DRM_HOST_OVERLAY_CANDIDATES_H_