media: Add MediaOzonePlatform support

media/ozone/media_ozone_platform.cc

+// Copyright 2014 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 "media/ozone/media_ozone_platform.h"
+
+#include "base/debug/trace_event.h"
+#include "base/logging.h"
+#include "ui/ozone/platform_object.h"
+#include "ui/ozone/platform_selection.h"
+
+namespace media {
+
+namespace {
+
+class MediaOzonePlatformStub : public MediaOzonePlatform {
+ public:
+  MediaOzonePlatformStub() {}
+
+  virtual ~MediaOzonePlatformStub() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MediaOzonePlatformStub);
+};
+
+}  // namespace
+
+// the following are just convenient stubs and need to be removed once the
+// internal platforms decide to actually implement their media specifics

[xhwang, 2014/06/09 23:53:34]

nit: Punctuation, Spelling and Grammar:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Punctu...

[vignatti (out of this project), 2014/06/10 14:50:29]

Done.

+
+MediaOzonePlatform* CreateMediaOzonePlatformCaca() {
+  return new MediaOzonePlatformStub;
+}
+
+MediaOzonePlatform* CreateMediaOzonePlatformDri() {
+  return new MediaOzonePlatformStub;
+}
+
+MediaOzonePlatform* CreateMediaOzonePlatformEgltest() {
+  return new MediaOzonePlatformStub;
+}
+
+MediaOzonePlatform* CreateMediaOzonePlatformGbm() {
+  return new MediaOzonePlatformStub;
+}
+
+MediaOzonePlatform* CreateMediaOzonePlatformTest() {
+  return new MediaOzonePlatformStub;
+}

[xhwang, 2014/06/09 23:53:34]

Are these declared by generate_constructor_list.py?

These creation functions are not used in this CL? Shall we add them later when
it's actually needed/used?

Can we just return NULL on platforms that doesn't support their own media
specifies?

[vignatti (out of this project), 2014/06/10 14:50:29]

Yes, these are used in this CL and declared by generate_constructor_list.py. If
just return NULL we would be deferring wrongly, per spang@ comment in
https://codereview.chromium.org/269673005/#msg42@

Done.

+
+MediaOzonePlatform::MediaOzonePlatform() {
+  CHECK(!instance_) << "There should only be a single MediaOzonePlatform.";
+  instance_ = this;
+}
+
+MediaOzonePlatform::~MediaOzonePlatform() {
+  CHECK_EQ(instance_, this);
+  instance_ = NULL;
+}
+
+// static
+MediaOzonePlatform* MediaOzonePlatform::GetInstance() {
+  if (!instance_)
+    CreateInstance();
+  return instance_;
+}
+
+VideoDecodeAccelerator* MediaOzonePlatform::CreateVideoDecodeAccelerator(
+    const base::Callback<bool(void)>& make_context_current) {
+  NOTIMPLEMENTED();
+  return NULL;
+}
+
+// static
+void MediaOzonePlatform::CreateInstance() {
+  if (!instance_) {

[xhwang, 2014/06/09 23:53:34]

nit: We like to return early:

if (instance_)
  return;

TRACE...
Create()...

[vignatti (out of this project), 2014/06/10 14:50:29]

Done.

+    TRACE_EVENT1("ozone",
+                 "MediaOzonePlatform::Initialize",
+                 "platform",
+                 ui::GetOzonePlatformName());
+    scoped_ptr<MediaOzonePlatform> platform =
+        ui::PlatformObject<MediaOzonePlatform>::Create();

[xhwang, 2014/06/09 23:53:34]

Is it possible to use base/lazy_instance.h for |instance_|?

[vignatti (out of this project), 2014/06/10 14:50:29]

I think we could but we preferred the other style just. I'm not sure.

[spang, 2014/06/10 15:24:23]

No, lazy instance can NOT be used when you do not know the concrete type. It
allocates the storage statically.

+
+    // TODO(spang): Currently need to leak this object.

[xhwang, 2014/06/09 23:53:34]

Is there a bug tracking this?

[vignatti (out of this project), 2014/06/10 14:50:29]

no, sorry.

[spang, 2014/06/10 15:37:40]

crbug.com/380884

+    CHECK_EQ(instance_, platform.release());
+  }
+}
+
+// static
+MediaOzonePlatform* MediaOzonePlatform::instance_;
+
+}  // namespace media