Implement right-to-left text rendering in Pepper.

ppapi/c/dev/ppb_font_dev.h

 /* 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.
  */
 
-/* From dev/ppb_font_dev.idl modified Tue Oct 11 10:01:39 2011. */
+/* From dev/ppb_font_dev.idl modified Mon Jun 25 14:54:48 2012. */
 
 #ifndef PPAPI_C_DEV_PPB_FONT_DEV_H_
 #define PPAPI_C_DEV_PPB_FONT_DEV_H_
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_macros.h"
 #include "ppapi/c/pp_point.h"
 #include "ppapi/c/pp_rect.h"
 #include "ppapi/c/pp_resource.h"
@@ skipping 117 matching lines @@
 PP_COMPILE_ASSERT_STRUCT_SIZE_IN_BYTES(PP_FontMetrics_Dev, 20);
 
 struct PP_TextRun_Dev {
   /**
    * This var must either be a string or a null/undefined var (which will be
    * treated as a 0-length string).
    */
   struct PP_Var text;
   /**
    * Set to PP_TRUE if the text is right-to-left.
+   *
+   * When <code>override_direction</code> is false, the browser will perform
+   * the Unicode Bidirectional Algorithm (http://unicode.org/reports/tr9/) on
+   * the text. The value of the <code>rtl</code> flag specifies the
+   * direcionality of the surrounding environment. This means that Hebrew
+   * word will always display right to left, even if <code>rtl</code> is false.
+   *
+   * When <code>override_direction</code> is true, no autodetection will be done
+   * and <code>rtl</code> specifies the direction of the text.
+   *
+   * TODO(brettw) note that autodetection with rtl = true is currently
+   * unimplemented.
    */
   PP_Bool rtl;
   /**
    * Set to PP_TRUE to force the directionality of the text regardless of
-   * content
+   * content.
+   *
+   * If this flag is set, the browser will skip autodetection of the content
+   * and will display all text in the direction speficied by the
+   * <code>rtl</code> flag.
    */
   PP_Bool override_direction;
 };
 PP_COMPILE_ASSERT_STRUCT_SIZE_IN_BYTES(PP_TextRun_Dev, 24);
 /**
  * @}
  */
 
 /**
  * @addtogroup Interfaces
@@ skipping 94 matching lines @@
                                      uint32_t char_offset);
 };
 
 typedef struct PPB_Font_Dev_0_6 PPB_Font_Dev;
 /**
  * @}
  */
 
 #endif  /* PPAPI_C_DEV_PPB_FONT_DEV_H_ */