Adds initial key systems support for Chromecast.

chromecast/media/media.gyp

Index: chromecast/media/media.gyp
diff --git a/chromecast/media/media.gyp b/chromecast/media/media.gyp
index 0674a9e63cc74fd605b27791940d127da87d7748..cc96d6a61154ae9716a07b6e4b9f246653525741 100644
--- a/chromecast/media/media.gyp
+++ b/chromecast/media/media.gyp
@@ -5,6 +5,19 @@
 {
   'targets': [
     {
+      'target_name': 'media_base',
+      'type': '<(component)',
+      'dependencies': [
+        '../../base/base.gyp:base',
+        '../../crypto/crypto.gyp:crypto',

[ddorwin, 2014/09/13 03:27:07]

Why?

[gunsch, 2014/09/15 21:43:38]

Eager copy from downstream, removed for this CL.

+        '../../third_party/widevine/cdm/widevine_cdm.gyp:widevine_cdm_version_h',

[ddorwin, 2014/09/13 03:27:07]

Do you have a modification to this .gyp?

[gunsch, 2014/09/15 21:43:38]

No, why?

We're adding the dependency because it a) causes a copy and b) IIRC has a
direct_dependent_settings + include_dirs combination so that
"widevine_cdm_version.h" gets included correctly.

[ddorwin, 2014/09/15 22:50:53]

This line copies the header file for the platform to the intermediate output
directory to be used by all the C++ code that needs it. Without modifying that
.gyp file, I think it would fail when building Chromecast. Maybe this change is
not yet upstreamed?

[gunsch, 2014/09/16 16:58:00]

It does not fail. It uses a default Linux implementation where Widevine is
disabled.

However, widevine_cdm.gyp exposes a "widevine_cdm_version_h_file" variable,
which we override conditionally based on if internal CDM code is available.

+      ],
+      'sources': [
+        'base/key_systems_common.cc',
+        'base/key_systems_common.h',
+      ],
+    },
+    {
       'target_name': 'cma_base',
       'type': '<(component)',
       'dependencies': [