Revise gamepad interface

webkit/plugins/ppapi/ppapi_plugin_instance.cc

Index: webkit/plugins/ppapi/ppapi_plugin_instance.cc
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.cc b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
index 1b6ff947aa7bfd1d22902ab6df17623914cb52df..662098a7ec0cc18709f57042b5c7e4eb760f5421 100644
--- a/webkit/plugins/ppapi/ppapi_plugin_instance.cc
+++ b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
@@ -220,15 +220,6 @@ COMPILE_ASSERT_MATCHING_ENUM(TypeGrabbing, PP_CURSORTYPE_GRABBING);
 // Do not assert WebCursorInfo::TypeCustom == PP_CURSORTYPE_CUSTOM;
 // PP_CURSORTYPE_CUSTOM is pinned to allow new cursor types.
 
-// Ensure conversion from WebKit::WebGamepads to PP_GamepadsData_Dev is safe.
-// See also DCHECKs in SampleGamepads below.
-//
-// Temporarily disabled for 2-sided WebKit roll.
-//COMPILE_ASSERT(sizeof(WebKit::WebGamepads) == sizeof(PP_GamepadsData_Dev),
-//               size_difference);
-//COMPILE_ASSERT(sizeof(WebKit::WebGamepad) == sizeof(PP_GamepadData_Dev),
-//               size_difference);
-
 // Sets |*security_origin| to be the WebKit security origin associated with the
 // document containing the given plugin instance. On success, returns true. If
 // the instance is invalid, returns false and |*security_origin| will be
@@ -1354,39 +1345,32 @@ bool PluginInstance::IsRectTopmost(const gfx::Rect& rect) {
 }
 
 void PluginInstance::SampleGamepads(PP_Instance instance,
-                                    PP_GamepadsData_Dev* data) {
-
-  // Because the WebKit objects have trivial ctors, using offsetof doesn't
-  // work. Instead use this version based on src/v8/src/globals.h. This
-  // workaround doesn't work in constant expressions as required for
-  // COMPILE_ASSERT, so DCHECK instead.
-
-#define OFFSET_OF(type, field) \
-  (reinterpret_cast<intptr_t>(&(reinterpret_cast<type*>(4)->field)) - 4)
-
-#define DCHECK_GAMEPADS_OFFSET(webkit_name, pp_name) \
-  DCHECK(OFFSET_OF(WebKit::WebGamepads, webkit_name) \
-             == OFFSET_OF(PP_GamepadsData_Dev, pp_name))
-
-#define DCHECK_GAMEPAD_OFFSET(webkit_name, pp_name) \
-  DCHECK(OFFSET_OF(WebKit::WebGamepad, webkit_name) \
-             == OFFSET_OF(PP_GamepadData_Dev, pp_name))
-
-  DCHECK_GAMEPADS_OFFSET(length, length);
-  DCHECK_GAMEPADS_OFFSET(items, items);
-  DCHECK_GAMEPAD_OFFSET(connected, connected);
-  DCHECK_GAMEPAD_OFFSET(id, id);
-  DCHECK_GAMEPAD_OFFSET(timestamp, timestamp);
-  DCHECK_GAMEPAD_OFFSET(axesLength, axes_length);
-  DCHECK_GAMEPAD_OFFSET(axes, axes);
-  DCHECK_GAMEPAD_OFFSET(buttonsLength, buttons_length);
-  DCHECK_GAMEPAD_OFFSET(buttons, buttons);
-
-#undef OFFSET_OF
-#undef DCHECK_GAMEPADS_OFFSET
-#undef DCHECK_GAMEPAD_OFFSET
-
-  delegate()->SampleGamepads(reinterpret_cast<WebKit::WebGamepads*>(data));
+                                    PP_GamepadsSampleData_Dev* data) {
+  WebKit::WebGamepads webkit_data;

[brettw, 2012/02/27 17:44:20]

I know it was already here, but can you move this code to event_conversion.cc?
This file is so large.

[scottmg, 2012/02/27 21:29:48]

Done.

+  delegate()->SampleGamepads(&webkit_data);
+
+  data->length = webkit_data.length;
+  for (unsigned i = 0; i < webkit_data.length; ++i) {
+    PP_GamepadSampleData_Dev& output_pad = data->items[i];
+    const WebKit::WebGamepad& webkit_pad = webkit_data.items[i];
+    output_pad.connected = webkit_pad.connected ? PP_TRUE : PP_FALSE;
+    if (webkit_pad.connected) {
+      COMPILE_ASSERT(sizeof(output_pad.id) == sizeof(webkit_pad.id),
+                     id_size_does_not_match);
+      COMPILE_ASSERT(sizeof(output_pad.axes) == sizeof(webkit_pad.axes),
+                     axes_size_does_not_match);
+      COMPILE_ASSERT(sizeof(output_pad.buttons) == sizeof(webkit_pad.buttons),
+                     buttons_size_does_not_match);
+      memcpy(output_pad.id, webkit_pad.id, sizeof(output_pad.id));
+      output_pad.timestamp = webkit_pad.timestamp;
+      output_pad.axes_length = webkit_pad.axesLength;
+      memcpy(output_pad.axes, webkit_pad.axes, sizeof(output_pad.axes));
+      output_pad.buttons_length = webkit_pad.buttonsLength;
+      memcpy(output_pad.buttons,
+             webkit_pad.buttons,
+             sizeof(output_pad.buttons));
+    }
+  }
 }
 
 bool PluginInstance::IsViewAccelerated() {