[Device Service] Move Gamepad Blink headers to be part of the Gamepad client library

third_party/WebKit/public/platform/WebGamepadListener.h

Index: third_party/WebKit/public/platform/WebGamepadListener.h
diff --git a/third_party/WebKit/public/platform/WebGamepadListener.h b/third_party/WebKit/public/platform/WebGamepadListener.h
index f2fbffc49ebde0a0a103370449f32714866ff5a2..75016fa803c05a521504464907f88b86f8682a26 100644
--- a/third_party/WebKit/public/platform/WebGamepadListener.h
+++ b/third_party/WebKit/public/platform/WebGamepadListener.h
@@ -7,14 +7,16 @@
 
 #include "WebPlatformEventListener.h"
 
-namespace blink {
+namespace device {
+class Gamepad;
+}
 
-class WebGamepad;
+namespace blink {
 
 class WebGamepadListener : public WebPlatformEventListener {
  public:
-  virtual void DidConnectGamepad(unsigned index, const WebGamepad&) = 0;
-  virtual void DidDisconnectGamepad(unsigned index, const WebGamepad&) = 0;
+  virtual void DidConnectGamepad(unsigned index, const device::Gamepad&) = 0;
+  virtual void DidDisconnectGamepad(unsigned index, const device::Gamepad&) = 0;
 
  protected:
   virtual ~WebGamepadListener() {}