Implement the gamepad API in the IPC proxy

ppapi/shared_impl/ppb_gamepad_shared.h

Index: ppapi/shared_impl/ppb_gamepad_shared.h
diff --git a/ppapi/shared_impl/ppb_gamepad_shared.h b/ppapi/shared_impl/ppb_gamepad_shared.h
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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_SHARED_IMPL_PPB_GAMEPAD_SHARED_H_
+#define PPAPI_SHARED_IMPL_PPB_GAMEPAD_SHARED_H_
+
+#include "base/atomicops.h"
+#include "base/string16.h"
+#include "ppapi/c/ppb_gamepad.h"
+#include "ppapi/shared_impl/ppapi_shared_export.h"
+
+namespace ppapi {
+
+// TODO(brettw) when we remove the non-IPC-based gamepad implementation, this
+// code should all move into the GamepadResource.
+
+#pragma pack(push, 1)
+
+// This must match the definition of WebKit::Gamepad. The GamepadHost unit test
+// has some compile asserts to validate this.
+struct WebKitGamepad {
+    static const size_t kIdLengthCap = 128;
+    static const size_t kAxesLengthCap = 16;
+    static const size_t kButtonsLengthCap = 32;
+
+    // Is there a gamepad connected at this index?
+    bool connected;
+
+    // Device identifier (based on manufacturer, model, etc.).
+    char16 id[kIdLengthCap];
+
+    // Monotonically increasing value referring to when the data were last
+    // updated.
+    unsigned long long timestamp;
+
+    // Number of valid entries in the axes array.
+    unsigned axes_length;
+
+    // Normalized values representing axes, in the range [-1..1].
+    float axes[kAxesLengthCap];
+
+    // Number of valid entries in the buttons array.
+    unsigned buttons_length;
+
+    // Normalized values representing buttons, in the range [0..1].
+    float buttons[kButtonsLengthCap];
+};
+
+// This must match the definition of WebKit::Gamepads. The GamepadHost unit
+// test has some compile asserts to validate this.
+struct WebKitGamepads {
+    static const size_t kItemsLengthCap = 4;
+
+    // Number of valid entries in the items array.
+    unsigned length;
+
+    // Gamepad data for N separate gamepad devices.
+    WebKitGamepad items[kItemsLengthCap];
+};
+
+// This is the structure store in shared memory. It must match
+// content/common/gamepad_hardware_buffer.h. The GamepadHost unit test has
+// some compile asserts to validate this.
+struct ContentGamepadHardwareBuffer {
+  base::subtle::Atomic32 sequence;
+  WebKitGamepads buffer;
+};
+
+#pragma pack(pop)
+
+PPAPI_SHARED_EXPORT void ConvertWebKitGamepadData(
+    const WebKitGamepads& webkit_data,
+    PP_GamepadsSampleData* output_data);
+
+}  // namespace ppapi
+
+#endif  // PPAPI_SHARED_IMPL_PPB_GAMEPAD_SHARED_H_