Bug 1254858: P8. Change default preferences value if prefs don't exist. r=kentuckyfriedtakahe

When running gtest, none of the prefs actually exist, so we end up having most PDMs disabled.

MozReview-Commit-ID: GNjhXtjKpGC

--HG--
extra : rebase_source : 3e5a931dd49c798cff9792e3a1c4ff2e5afc4a83

dom/media/fmp4/MP4Decoder.cpp

@@ -180,7 +180,7 @@ MP4Decoder::CanHandleMediaType(const nsAString& aContentType)
 bool
 MP4Decoder::IsEnabled()
 {
-  return Preferences::GetBool("media.mp4.enabled");
+  return Preferences::GetBool("media.mp4.enabled", true);
 }
 
 // sTestH264ExtraData represents the content of the avcC atom found in

dom/media/platforms/PDMFactory.cpp

@@ -82,10 +82,10 @@ PDMFactory::Init()
   alreadyInitialized = true;
 
   Preferences::AddBoolVarCache(&sUseBlankDecoder,
-                               "media.use-blank-decoder");
+                               "media.use-blank-decoder", false);
 #ifdef MOZ_GONK_MEDIACODEC
   Preferences::AddBoolVarCache(&sGonkDecoderEnabled,
-                               "media.gonk.enabled", false);
+                               "media.gonk.enabled", true);
 #endif
 #ifdef MOZ_WIDGET_ANDROID
   Preferences::AddBoolVarCache(&sAndroidMCDecoderEnabled,
@@ -95,18 +95,18 @@ PDMFactory::Init()
 #endif
 
   Preferences::AddBoolVarCache(&sGMPDecoderEnabled,
-                               "media.gmp.decoder.enabled", false);
+                               "media.gmp.decoder.enabled", true);
 #ifdef MOZ_FFMPEG
   Preferences::AddBoolVarCache(&sFFmpegDecoderEnabled,
-                               "media.ffmpeg.enabled", false);
+                               "media.ffmpeg.enabled", true);
 #endif
 #ifdef MOZ_FFVPX
   Preferences::AddBoolVarCache(&sFFVPXDecoderEnabled,
-                               "media.ffvpx.enabled", false);
+                               "media.ffvpx.enabled", true);
 #endif
 #ifdef XP_WIN
   Preferences::AddBoolVarCache(&sWMFDecoderEnabled,
-                               "media.wmf.enabled", false);
+                               "media.wmf.enabled", true);
 #endif
 
   Preferences::AddBoolVarCache(&sEnableFuzzingWrapper,