Replace media::Limits struct with media::limits namespace and update documentation.

media/base/limits.h

 // Copyright (c) 2011 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.
 
 // Contains limit definition constants for the media subsystem.
 
 #ifndef MEDIA_BASE_LIMITS_H_
 #define MEDIA_BASE_LIMITS_H_
 
 #include "base/basictypes.h"
 
 namespace media {
 
-struct Limits {
-  // For video.
-  static const int kMaxDimension = (1 << 15) - 1;  // 32767
-  static const int kMaxCanvas = (1 << (14 * 2));  // 16384 x 16384
+namespace limits {
 
-  // Total number of video frames which are populating in the pipeline.
-  static const size_t kMaxVideoFrames = 4;
+// Maximum possible dimension (width or height) for any video.
+static const int kMaxDimension = (1 << 15) - 1;  // 32767

[Ami GONE FROM CHROMIUM, 2011/12/03 02:11:38]

Drop the statics everywhere in this file.
Right now what you're doing is creating storage for each of these vars in every
compilation unit that includes this .h.

The right way to do this is to declare these consts extern here but define them
in a (new) limits.cc file.  That way storage is only allocated once.

Alternatively, you could use an anonymous enum (assuming none of these ever have
their address taken).  Personally that's my favorite approach.

[scherkus (not reviewing), 2011/12/06 02:05:57]

Done.

 
-  // Following limits are used by AudioParameters::IsValid().
-  // The 192 Khz constant is the frequency of quicktime lossless audio codec.
-  // MP4 is limited to 96 Khz, and mp3 is limited to 48 Khz.
-  // OGG vorbis was initially limited to 96 Khz, but recent tools are unlimited.
-  // 192 Khz is also the limit on most PC audio hardware.
-  static const int kMaxSampleRate = 192000;
-  static const int kMinSampleRate = 8000;
-  static const int kMaxChannels = 32;
-  static const int kMaxBitsPerSample = 64;
-  static const int kMaxSamplesPerPacket = kMaxSampleRate;
+// Maximum possible canvas size (width multiplied by height) for any video.
+static const int kMaxCanvas = (1 << (14 * 2));  // 16384 x 16384
 
-  // Maximum possible time.
-  static const int64 kMaxTimeInMicroseconds = kint64max;
-};
+// Total number of video frames which are populating in the pipeline.
+static const size_t kMaxVideoFrames = 4;
+
+// Following limits are used by AudioParameters::IsValid().

[Ami GONE FROM CHROMIUM, 2011/12/03 02:11:38]

s/Following/The following/

[scherkus (not reviewing), 2011/12/06 02:05:57]

Done.

[Ami GONE FROM CHROMIUM, 2011/12/07 01:04:48]

Nope.

+//
+// A few notes on samples rates of common formats:

[Ami GONE FROM CHROMIUM, 2011/12/03 02:11:38]

s/samples/sample/

+//   - AAC files are limited to 96 Khz.

[Ami GONE FROM CHROMIUM, 2011/12/03 02:11:38]

s/Khz/kHz/ here and below.

[scherkus (not reviewing), 2011/12/06 02:05:57]

Done.

+//   - MP3 files are limited to 48 Khz.
+//   - Vorbis used to be limited to 96 KHz, but no longer has that restriction.
+//   - Most PC audio hardware is limited to 192 KHz.
+static const int kMaxSampleRate = 192000;
+static const int kMinSampleRate = 8000;
+static const int kMaxChannels = 32;
+static const int kMaxBitsPerSample = 64;
+static const int kMaxSamplesPerPacket = kMaxSampleRate;
+
+// Maximum possible time.
+static const int64 kMaxTimeInMicroseconds = kint64max;

[Ami GONE FROM CHROMIUM, 2011/12/03 02:11:38]

This should die.  See my specific comments at call-sites.

[scherkus (not reviewing), 2011/12/06 02:05:57]

Done.

+
+}  // namespace limits
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_LIMITS_H_