aw: Add versions to public function tables

android_webview/public/browser/draw_gl.h

 // Copyright 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 ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_GL_H_
 #define ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_GL_H_
 
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ skipping 68 matching lines @@
 typedef void AwReleaseGraphicBufferFunction(long buffer_id);
 // Called to map a GraphicBuffer in |mode|.
 typedef int AwMapFunction(long buffer_id, AwMapMode mode, void** vaddr);
 // Called to unmap a GraphicBuffer
 typedef int AwUnmapFunction(long buffer_id);
 // Called to get a native buffer pointer
 typedef void* AwGetNativeBufferFunction(long buffer_id);
 // Called to get the stride of the buffer
 typedef unsigned int AwGetStrideFunction(long buffer_id);
 
+static const int kAwDrawGLFunctionTableVersion = 1;

[hush (inactive), 2014/07/31 21:03:50]

what is the circumstance that AwDrawGLFunctionTableVersion is different from
AwDrawGLInfoVersion? Should they always be the same version?

[hush (inactive), 2014/07/31 21:08:40]

I guess every time you add something to the struct, you need to increase the
version number by 1. And you are not supposed to delete members from the struct.
Right?
On 2014/07/31 21:03:50, hush wrote:

[boliu, 2014/07/31 21:09:38]

They can change independently. For example if we switch to idle upload, we can
drop all the gralloc functions from the table below, which is ehh...everything.
But nothing changes to AwDrawGLInfoVersion

[boliu, 2014/07/31 21:10:46]

Right that's the idea. And you can't access new members based on version.

Binary stability..

+
 // Set of functions used in rendering in hardware mode
 struct AwDrawGLFunctionTable {
+  int version;
   AwCreateGraphicBufferFunction* create_graphic_buffer;
   AwReleaseGraphicBufferFunction* release_graphic_buffer;
   AwMapFunction* map;
   AwUnmapFunction* unmap;
   AwGetNativeBufferFunction* get_native_buffer;
   AwGetStrideFunction* get_stride;
 };
 
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_GL_H_