Extracted hardcoded constants from cast_rtp_stream.

media/cast/cast_defines.h

Index: media/cast/cast_defines.h
diff --git a/media/cast/cast_defines.h b/media/cast/cast_defines.h
index 9bf2f44352cf4349364a73670b95b9cdf71672ed..a91c7e2cbc2197d287fde962c8ec6e27ed3aacd0 100644
--- a/media/cast/cast_defines.h
+++ b/media/cast/cast_defines.h
@@ -23,6 +23,7 @@ namespace cast {
 const int64 kDontShowTimeoutMs = 33;

[mcasas, 2015/09/15 16:59:39]

I think this is never used, so please remove.
(But it might be, in unindexed locations)

[msu.koo, 2015/09/17 07:00:50]

Done.

 const float kDefaultCongestionControlBackOff = 0.875f;

[mcasas, 2015/09/15 16:59:39]

This is only used once in [1], suggest moving it there :)

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/media/cast/cast_co...

[msu.koo, 2015/09/17 07:00:50]

Done.

 const uint32 kVideoFrequency = 90000;
+const int kMinSampleRateForEncoding = 8000;

[mcasas, 2015/09/15 16:59:39]

s/int/uint32_t/

I personally like writing 8000u for unsigned constants, but
that's not pervasive in the code base. Just makes it easier
to read IMHO.

[miu, 2015/09/15 22:05:22]

The "int" is more correct, per style guide
(https://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Integer_Types).

We're trying to get rid of uses of unsigned ints in media/cast code wherever we
can (style guide discussion explains why they are bad).  In media/cast code, the
only allowed cases (in new code) are:

1. Bit manipulation, wire-format (de)serialization.  This includes blob/opaque
data (e.g., use of uint8 to indicate byte-sized binary payloads).

2. In cases where size_t should be used.

3. Where wrap-around "counter" semantics are a part of the design (though this
has caused us headaches, and we're looking to replace these unsigneds with class
types).

[msu.koo, 2015/09/17 07:00:50]

Acknowledged.

 const uint32 kStartFrameId = UINT32_C(0xffffffff);
 
 // This is an important system-wide constant.  This limits how much history the