Cleanup: Remove unneeded forward declarations from remoting.

remoting/host/host_config.h

Index: remoting/host/host_config.h
===================================================================
--- remoting/host/host_config.h	(revision 109590)
+++ remoting/host/host_config.h	(working copy)
@@ -9,8 +9,6 @@
 
 #include "base/memory/ref_counted.h"
 
-class Task;
-
 namespace remoting {
 
 // Following constants define names for configuration parameters.
@@ -34,8 +32,8 @@
 // HostConfig interace provides read-only access to host configuration.
 class HostConfig : public base::RefCountedThreadSafe<HostConfig> {
  public:
-  HostConfig() { };
-  virtual ~HostConfig() { }
+  HostConfig() {}
+  virtual ~HostConfig() {}
 
   virtual bool GetString(const std::string& path, std::string* out_value) = 0;
   virtual bool GetBoolean(const std::string& path, bool* out_value) = 0;
@@ -46,7 +44,7 @@
 // MutableHostConfig extends HostConfig for mutability.
 class MutableHostConfig : public HostConfig {
  public:
-  MutableHostConfig() { };
+  MutableHostConfig() {}
 
   // SetString() updates specified config value. Save() must be called to save
   // the changes on the disk.