bug 852935 - Add Android gamepad backend. r=snorp, rs=smaug

widget/android/AndroidJavaWrappers.h

@@ -537,6 +537,11 @@ public:
     RefCountedJavaObject* ByteBuffer() { return mByteBuffer; }
     int Width() { return mWidth; }
     int Height() { return mHeight; }
+    int ID() { return mID; }
+    int GamepadButton() { return mGamepadButton; }
+    bool GamepadButtonPressed() { return mGamepadButtonPressed; }
+    float GamepadButtonValue() { return mGamepadButtonValue; }
+    const nsTArray<float>& GamepadValues() { return mGamepadValues; }
     int RequestId() { return mCount; } // for convenience
     WidgetTouchEvent MakeTouchEvent(nsIWidget* widget);
     MultiTouchInput MakeMultiTouchInput(nsIWidget* widget);
@@ -574,6 +579,11 @@ protected:
     short mScreenOrientation;
     nsRefPtr<RefCountedJavaObject> mByteBuffer;
     int mWidth, mHeight;
+    int mID;
+    int mGamepadButton;
+    bool mGamepadButtonPressed;
+    float mGamepadButtonValue;
+    nsTArray<float> mGamepadValues;
     nsCOMPtr<nsIObserver> mObserver;
     nsTArray<nsString> mPrefNames;
 
@@ -652,6 +662,12 @@ protected:
     static jfieldID jWidthField;
     static jfieldID jHeightField;
 
+    static jfieldID jIDField;
+    static jfieldID jGamepadButtonField;
+    static jfieldID jGamepadButtonPressedField;
+    static jfieldID jGamepadButtonValueField;
+    static jfieldID jGamepadValuesField;
+
     static jclass jDomKeyLocationClass;
     static jfieldID jDomKeyLocationValueField;
 
@@ -693,6 +709,8 @@ public:
         TELEMETRY_UI_SESSION_START = 42,
         TELEMETRY_UI_SESSION_STOP = 43,
         TELEMETRY_UI_EVENT = 44,
+        GAMEPAD_ADDREMOVE = 45,
+        GAMEPAD_DATA = 46,
         dummy_java_enum_list_end
     };
 
@@ -719,6 +737,16 @@ public:
         IME_ACKNOWLEDGE_FOCUS = 6,
         dummy_ime_enum_list_end
     };
+
+    enum {
+        ACTION_GAMEPAD_ADDED = 1,
+        ACTION_GAMEPAD_REMOVED = 2
+    };
+
+    enum {
+        ACTION_GAMEPAD_BUTTON = 1,
+        ACTION_GAMEPAD_AXES = 2
+    };
 };
 
 class nsJNIString : public nsString