Minor changes to the comments of ResourceTracker and PP_ImageDataFormat.

ppapi/c/ppb_image_data.h

Index: ppapi/c/ppb_image_data.h
diff --git a/ppapi/c/ppb_image_data.h b/ppapi/c/ppb_image_data.h
index bc014d4e73cc7275249ae9a73da220d55511866d..c25615f8d4f088111639ef76217f477e2b3e9738 100644
--- a/ppapi/c/ppb_image_data.h
+++ b/ppapi/c/ppb_image_data.h
@@ -27,6 +27,11 @@
 /**
  * PP_ImageDataFormat is an enumeration of the different types of
  * image data formats.
+ *
+ * The third part of each enumeration value describes the memory layout from
+ * the lowest address to the highest. For example, BGRA means the B component
+ * is stored in the lowest address, no matter what endianness the platform is
+ * using.
  */
 typedef enum {
   PP_IMAGEDATAFORMAT_BGRA_PREMUL,
@@ -170,4 +175,3 @@ struct PPB_ImageData {
  */
 
 #endif  /* PPAPI_C_PPB_IMAGE_DATA_H_ */
-