Put the Pepper stuff in the content namespace.

content/renderer/pepper/pepper_platform_audio_output_impl.h

Index: content/renderer/pepper/pepper_platform_audio_output_impl.h
diff --git a/content/renderer/pepper/pepper_platform_audio_output_impl.h b/content/renderer/pepper/pepper_platform_audio_output_impl.h
index f1d5cba044f13c12d23e5b285fd7af93a194f466..8c5fb95c0ba70d0af1a2c1ffce2b706741fd294e 100644
--- a/content/renderer/pepper/pepper_platform_audio_output_impl.h
+++ b/content/renderer/pepper/pepper_platform_audio_output_impl.h
@@ -16,6 +16,8 @@ namespace base {
 class MessageLoopProxy;
 }
 
+namespace content {
+
 class PepperPlatformAudioOutputImpl
     : public webkit::ppapi::PluginDelegate::PlatformAudioOutput,
       public AudioMessageFilter::Delegate,
@@ -72,4 +74,6 @@ class PepperPlatformAudioOutputImpl
   DISALLOW_COPY_AND_ASSIGN(PepperPlatformAudioOutputImpl);
 };
 
+}  // namespace content
+
 #endif  // CONTENT_RENDERER_PEPPER_PEPPER_PLATFORM_AUDIO_OUTPUT_IMPL_H_