Linux: fix build with system ffmpeg (Chromium side).

media/base/media_posix.cc

Index: media/base/media_posix.cc
diff --git a/media/base/media_posix.cc b/media/base/media_posix.cc
index ff50287ba6a678b11c1bf009c811efab25208296..26a08c440626466a4f93986c2e97af4147bb60da 100644
--- a/media/base/media_posix.cc
+++ b/media/base/media_posix.cc
@@ -52,6 +52,11 @@ static bool g_media_library_is_initialized = false;
 static bool InitializeMediaLibraryInternal(const FilePath& module_dir) {
   DCHECK(!g_media_library_is_initialized);
 
+#if defined(USE_SYSTEM_FFMPEG)
+  // No initialization is necessary when using system ffmpeg,
+  // we just link directly with system ffmpeg libraries.
+  g_media_library_is_initialized = true;
+#else
   StubPathMap paths;
 
   // First try to initialize with Chrome's sumo library.
@@ -67,6 +72,7 @@ static bool InitializeMediaLibraryInternal(const FilePath& module_dir) {
       FILE_PATH_LITERAL(DSO_NAME("avformat", AVFORMAT_VERSION))).value());
 
   g_media_library_is_initialized = InitializeStubs(paths);
+#endif  // !defined(USE_SYSTEM_FFMPEG)
   return g_media_library_is_initialized;
 }