Revise gamepad interface

Per API review, revision to gamepad interface. Still in _dev for now, will move to stable as separate change once we're happy with the interface.

Change summary:
- renames of various fields, and main function in idl per discussion
- timestamp to double, connected to PP_Bool
- remove #pragma pack in header, now copied member-by-member
- update examples

One complication was in removing the #pragma pack. Copying by member in webkit/plugins/ppapi/ppapi_plugin_instance.cc avoids the need to keep webkit and pepper in sync and exactly the same layout (a good thing).

However, when the native_client ppapi proxy is going between 32 and 64 the data structure ends up being a different size due to padding (all the fields are teh same sizes though). To workaround this, I added padding fields, and assert_sizes to confirm the sizes are the same on both "sides". This is similar to how PP_Point, input events, etc. get rpc'd, but perhaps there's a better way.

BUG=112879

Review URL: http://codereview.chromium.org/9405033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@124375 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 39 insertions, 43 deletions

diff --git a/webkit/plugins/ppapi/event_conversion.cc b/webkit/plugins/ppapi/event_conversion.cc
index 9936ce3..cfc74a9 100644
--- a/webkit/plugins/ppapi/event_conversion.cc
+++ b/webkit/plugins/ppapi/event_conversion.cc
@@ -16,6 +16,7 @@
 #include "ppapi/shared_impl/ppb_input_event_shared.h"
 #include "ppapi/shared_impl/time_conversion.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebGamepads.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 #include "webkit/plugins/ppapi/common.h"
 #include "webkit/plugins/ppapi/usb_key_code_conversion.h"
@@ -522,5 +523,31 @@ PP_InputEvent_Class ClassifyInputEvent(WebInputEvent::Type type) {
   }
 }
 
+void ConvertWebKitGamepadData(WebKit::WebGamepads& webkit_data,
+                              PP_GamepadsSampleData_Dev* output_data) {
+  output_data->length = webkit_data.length;
+  for (unsigned i = 0; i < webkit_data.length; ++i) {
+    PP_GamepadSampleData_Dev& output_pad = output_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));
+    }
+  }
+}
+
 }  // namespace ppapi
 }  // namespace webkit
diff --git a/webkit/plugins/ppapi/event_conversion.h b/webkit/plugins/ppapi/event_conversion.h
index b9b4004..573e5b6 100644
--- a/webkit/plugins/ppapi/event_conversion.h
+++ b/webkit/plugins/ppapi/event_conversion.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/memory/linked_ptr.h"
+#include "ppapi/c/dev/ppb_gamepad_dev.h"
 #include "ppapi/c/ppb_input_event.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebInputEvent.h"
 
@@ -18,6 +19,7 @@ struct InputEventData;
 }
 
 namespace WebKit {
+class WebGamepads;
 class WebInputEvent;
 }
 
@@ -47,6 +49,11 @@ std::vector<linked_ptr<WebKit::WebInputEvent> > CreateSimulatedWebInputEvents(
 // type should not be "Undefined" since there's no corresponding PPAPI class.
 PP_InputEvent_Class ClassifyInputEvent(WebKit::WebInputEvent::Type type);
 
+// Translate from WebGamepads to the Gamepad API format
+// PP_GamepadsSampleData_Dev.
+void ConvertWebKitGamepadData(WebKit::WebGamepads& webkit_data,
+                              PP_GamepadsSampleData_Dev* output_data);
+
 }  // namespace ppapi
 }  // namespace webkit
 
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.cc b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
index 7dde8d7..a5d6515 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 +1345,10 @@ 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;
+  delegate()->SampleGamepads(&webkit_data);
+  ConvertWebKitGamepadData(webkit_data, data);
 }
 
 bool PluginInstance::IsViewAccelerated() {
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.h b/webkit/plugins/ppapi/ppapi_plugin_instance.h
index 65f8475..b81a3e8 100644
--- a/webkit/plugins/ppapi/ppapi_plugin_instance.h
+++ b/webkit/plugins/ppapi/ppapi_plugin_instance.h
@@ -295,7 +295,7 @@ class WEBKIT_PLUGINS_EXPORT PluginInstance :
   bool IsRectTopmost(const gfx::Rect& rect);
 
   // Implementation of PPB_Gamepad.
-  void SampleGamepads(PP_Instance instance, PP_GamepadsData_Dev* data)
+  void SampleGamepads(PP_Instance instance, PP_GamepadsSampleData_Dev* data)
       OVERRIDE;
 
   // Implementation of PPP_Messaging.