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..3cebc65631390b030fed5789ea312516d005f8ea 100644
--- a/chromecast/media/media.gyp
+++ b/chromecast/media/media.gyp
@@ -3,8 +3,34 @@
 # found in the LICENSE file.
 
 {
+  'variables': {
+    'chromecast_branding%': 'Chromium',
+  },
   'targets': [
     {
+      'target_name': 'media_base',
+      'type': '<(component)',
+      'dependencies': [
+        '../../base/base.gyp:base',
+        '../../third_party/widevine/cdm/widevine_cdm.gyp:widevine_cdm_version_h',
+      ],
+      'sources': [
+        'base/key_systems_common.cc',
+        'base/key_systems_common.h',
+      ],
+      'conditions': [
+        ['chromecast_branding=="Chrome"', {
+          'dependencies': [
+            'internal/chromecast_internal.gyp:media_base_internal',
+          ],
+        }, {
+          'sources': [
+            'base/key_systems_common_simple.cc',
+          ],
+        }],
+      ],
+    },
+    {
       'target_name': 'cma_base',
       'type': '<(component)',
       'dependencies': [