Cleanup webaudio related header inclusions in HTMLMediaElement

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 0a528db4f758241281d6d01441c1fab6bbb26998..eb3b777d84325ee61b74defe2511bd6940300fd9 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -32,11 +32,14 @@
 #include "core/html/HTMLElement.h"
 #include "core/html/track/TextTrack.h"
 #include "platform/Supplementable.h"
-#include "platform/audio/AudioSourceProvider.h"
-#include "public/platform/WebAudioSourceProviderClient.h"
 #include "public/platform/WebMediaPlayerClient.h"
 #include "public/platform/WebMimeRegistry.h"
 
+#if ENABLE(WEB_AUDIO)
+#include "platform/audio/AudioSourceProvider.h"
+#include "public/platform/WebAudioSourceProviderClient.h"
+#endif
+
 namespace blink {
 class WebInbandTextTrack;
 class WebLayer;
@@ -45,8 +48,8 @@ class WebLayer;
 namespace blink {
 
 #if ENABLE(WEB_AUDIO)
-class AudioSourceProvider;
 class AudioSourceProviderClient;
+class WebAudioSourceProvider;

[philipj_slow, 2015/07/31 07:33:40]

This wasn't here before, why is it needed now?

[Srirama, 2015/07/31 07:38:49]

It is indirectly included previously(WebMediaPlayerClient->WebMediaPlayer).
I just remember one of the review comment from David in my previous patch that,
IWYU(Include What You Use). So i thought it is better to include directly.

[philipj_slow, 2015/07/31 08:46:31]

This isn't an include, but yeah, it used in this header without an include, so
good!

 #endif
 class AudioTrackList;
 class ContentType;