Shuffle media-related WebMimeRegistry code from webkit/ to content/.

content/shell/app/shell_main_delegate.cc

Index: content/shell/app/shell_main_delegate.cc
diff --git a/content/shell/app/shell_main_delegate.cc b/content/shell/app/shell_main_delegate.cc
index 6064067f2db4b303f85b2ee1040493c920a7070c..ee4f2c83cd9b016698a19d2f0c6f7e6ac5314ce3 100644
--- a/content/shell/app/shell_main_delegate.cc
+++ b/content/shell/app/shell_main_delegate.cc
@@ -142,6 +142,13 @@ bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
       command_line.AppendSwitch(switches::kEnableSoftwareCompositingGLAdapter);
 
     net::CookieMonster::EnableFileScheme();
+
+    // Unless/until WebM files are added to the media layout tests, we need to
+    // avoid removing MP4/H264/AAC so that layout tests can run on Android.
+#if !defined(OS_ANDROID)
+    net::RemoveProprietaryMediaTypesAndCodecsForTests();
+#endif
+
     if (!WebKitTestPlatformInitialize()) {
       if (exit_code)
         *exit_code = 1;