[PPAPI][MediaStream] Support configure for video input.

ppapi/shared_impl/media_stream_video_track_shared.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 "ppapi/shared_impl/media_stream_video_track_shared.h"
+
+#include "base/logging.h"
+
+namespace {
+
+const int32_t kMaxWidth = 4069;

[yzshen1, 2014/02/13 19:23:26]

why 4069 but not 4096? :)

[Peng, 2014/02/13 21:28:34]

oops! Done

+const int32_t kMaxHeight = 4069;
+
+}  // namespace
+
+namespace ppapi {
+
+// static
+bool MediaStreamVideoTrackShared::VerifyAttributes(
+    const Attributes& attributes) {
+  if (attributes.mask & Attributes::MASK_BUFFERS) {
+    if (attributes.buffers < 0)

[yzshen1, 2014/02/13 19:23:26]

I think it should be <= 0 here, right?

[Peng, 2014/02/13 21:28:34]

buffers == 0 means using default value.

[yzshen1, 2014/02/14 18:25:43]

Do you mean the plugin can, say, first use Configure to set buffers to a
non-default value; and then later use Configure with buffer==0 to set it back to
default value?
Please talk about it in the API definition.

An alternative is that everytime Configure is called, all attributes will be
reset, and those unspecified ones will be reset to their default values. Then we
don't need to support buffers==0, format==PP_VIDEOFRAME_FORMAT_UNKNOWN, etc.

[Peng, 2014/02/14 20:04:49]

Yes. It provides a way to set an attribute back to the default value.

I update doc of the API. Done

+      return false;
+  } else if (attributes.buffers) {

[yzshen1, 2014/02/13 19:23:26]

Please use explicit numeric check (here and below). 

[Peng, 2014/02/13 21:28:34]

Sorry. I don't understand this comment. Please rephrase it.

+    return false;
+  }
+
+  if (attributes.mask & Attributes::MASK_FORMAT) {
+    if (attributes.format < PP_VIDEOFRAME_FORMAT_UNKNOWN ||

[yzshen1, 2014/02/13 19:23:26]

maybe <=?

[Peng, 2014/02/13 21:28:34]

Same, if format == PP_VIDEOFRAME_FORMAT_UNKNOWN, chrome will use the default
format.

+        attributes.format > PP_VIDEOFRAME_FORMAT_LAST) {
+      return false;
+    }
+  } else if (attributes.format) {
+    return false;
+  }
+
+  if (attributes.mask & Attributes::MASK_WIDTH) {
+    if (attributes.width < 0 || attributes.width > kMaxWidth)

[yzshen1, 2014/02/13 19:23:26]

Maybe <= 0?

[Peng, 2014/02/13 21:28:34]

same. if width == 0, chrome will use the source video's width.

+      return false;
+    if (attributes.width & 0x3)
+      return false;
+  } else if (attributes.width) {
+    return false;
+  }
+
+  if (attributes.mask & Attributes::MASK_HEIGHT) {
+    if (attributes.height < 0 || attributes.height > kMaxHeight)

[yzshen1, 2014/02/13 19:23:26]

Maybe <= 0?

[Peng, 2014/02/13 21:28:34]

same to width.

+      return false;
+    if (attributes.height & 0x3)
+      return false;
+  } else if (attributes.height) {
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace ppapi