cc: Add BeginFrameArgs

cc/output/begin_frame_args.h

+// Copyright (c) 2013 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 CC_OUTPUT_BEGIN_FRAME_H_
+#define CC_OUTPUT_BEGIN_FRAME_H_
+
+#include "base/time.h"
+#include "cc/base/cc_export.h"
+#include "ipc/ipc_param_traits.h"
+
+namespace cc {
+
+class CC_EXPORT BeginFrameArgs {
+ public:
+  BeginFrameArgs();

[Sami, 2013/06/13 10:01:07]

Can we make this default constructor private/protected? Or maybe drop it
completely (and the explicit destructor too)?

[brianderson, 2013/06/14 20:12:02]

Sure. To do so, we will also need to add a CreateEmpty for initialization of
member variables.

[brianderson, 2013/06/14 21:07:18]

Actually, to send this as a message, we need a default constructor. I will have
the default constructor create an invalid set of values.

+  ~BeginFrameArgs();
+
+  // You should be able to find all instances where a BeginFrame has been
+  // created or propogated/modified by searching for "CreateBeginFrame".
+  static BeginFrameArgs CreateBeginFrame(base::TimeTicks frame_time,

[Sami, 2013/06/13 10:01:07]

Bikeshed: drop the "BeginFrame", it's cleaner :)
Create/CreateForSynchronousCompositor/CreateForTesting.

[brianderson, 2013/06/14 20:12:02]

Sounds good.

+                                         base::TimeTicks deadline,
+                                         base::TimeDelta interval);
+  static BeginFrameArgs CreateBeginFrameForSynchronousCompositor();
+  static BeginFrameArgs CreateBeginFrameForTesting();
+
+  // This is the default delta that will be used to adjust the deadline when
+  // proper draw-time estimations are not yet available.
+  static base::TimeDelta DefaultDeadlineAdjustment();

[Sami, 2013/06/13 10:01:07]

Could this be a static constant or do you think we'll have some fancier
algorithm here in the future?

[brianderson, 2013/06/14 20:12:02]

I wanted to make this a function in case we wanted to have it return different
values depending on the platform.

+
+  base::TimeTicks frame_time() const {
+    return frame_time_;
+  }
+
+  base::TimeTicks deadline() const {
+    return deadline_;
+  }
+
+  base::TimeDelta interval() const {
+    return interval_;
+  }
+
+ private:
+  friend class IPC::ParamTraits<BeginFrameArgs>;
+
+  BeginFrameArgs(base::TimeTicks frame_time,
+                 base::TimeTicks deadline,
+                 base::TimeDelta interval);
+
+  base::TimeTicks frame_time_;
+  base::TimeTicks deadline_;
+  base::TimeDelta interval_;
+};
+
+}  // namespace cc
+
+#endif  // CC_OUTPUT_BEGIN_FRAME_H_