Remove some Cobalt customizations from //media (#3118)

1. Replace the definition `MEDIA_IMPLEMENTATION` in //media/BUILD.gn
with `IS_MEDIA_IMPL`, the latter is used by the Chromium
`COMPONENT_EXPORT()` macro.
2. Remove some `#defined(STARBOARD)` guards for code that now built
without the guards.

b/338100595

Change-Id: I11c23dea33cb05428ce9b2d90e0b595c2851c628

media/BUILD.gn

@@ -30,7 +30,7 @@ config("media_config") {
     ]
   }
 
-  defines = [ "MEDIA_IMPLEMENTATION" ]
+  defines = [ "IS_MEDIA_IMPL" ]
 }
 
 config("media_config_public") {
@@ -82,6 +82,8 @@ component("media") {
     "base/encryption_pattern.h",
     "base/encryption_scheme.cc",
     "base/encryption_scheme.h",
+    "base/media_client.cc",
+    "base/media_client.h",
     "base/media_log.h",
     "base/media_resource.cc",
     "base/media_resource.h",

media/base/media_switches.h

@@ -452,12 +452,10 @@ enum class kCrosGlobalMediaControlsPinOptions {
   kHeuristic,
 };
 
-#if !defined(STARBOARD)
 // Feature param used to force default pin/unpin for global media controls in
 // CrOS.
 MEDIA_EXPORT extern const base::FeatureParam<kCrosGlobalMediaControlsPinOptions>
     kCrosGlobalMediaControlsPinParam;
-#endif  // !defined(STARBOARD)
 
 // Return bitmask of audio formats supported by EDID.
 MEDIA_EXPORT uint32_t GetPassthroughAudioFormats();

media/base/supported_types.cc

@@ -326,18 +326,14 @@ bool IsAACSupported(const AudioType& type) {
 }  // namespace
 
 bool IsSupportedAudioType(const AudioType& type) {
-#if !defined(STARBOARD)
   if (auto* media_client = GetMediaClient())
     return media_client->IsSupportedAudioType(type);
-#endif  // !defined(STARBOARD)
   return IsDefaultSupportedAudioType(type);
 }
 
 bool IsSupportedVideoType(const VideoType& type) {
-#if !defined(STARBOARD)
   if (auto* media_client = GetMediaClient())
     return media_client->IsSupportedVideoType(type);
-#endif  // !defined(STARBOARD)
   return IsDefaultSupportedVideoType(type);
 }