Linux: use generated shim headers for system mesa.

gpu/GLES2/gl2extchromium.h

Index: gpu/GLES2/gl2extchromium.h
diff --git a/gpu/GLES2/gl2extchromium.h b/gpu/GLES2/gl2extchromium.h
index 0175740c87fc239159dff00fcd0ecb47036127fd..f24fedbdfaa386eb2037c121eaa6065a74baf344 100644
--- a/gpu/GLES2/gl2extchromium.h
+++ b/gpu/GLES2/gl2extchromium.h
@@ -297,6 +297,34 @@ typedef void (
 #endif
 #endif  /* GL_CHROMIUM_texture_compression_dxt3 */
 
+/* GL_ANGLE_instanced_arrays */
+#ifndef GL_ANGLE_instanced_arrays
+#define GL_ANGLE_instanced_arrays 1
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY glDrawArraysInstancedANGLE(
+    GLenum mode, GLint first, GLsizei count, GLsizei primcount);
+#endif
+typedef void (
+    GL_APIENTRYP PFNGLDRAWARRAYSINSTANCEDANGLEPROC) (
+        GLenum mode, GLint first, GLsizei count, GLsizei primcount);
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY glDrawElementsInstancedANGLE(
+    GLenum mode, GLsizei count, GLenum type, const void* indices,
+    GLsizei primcount);
+#endif
+typedef void (
+    GL_APIENTRYP PFNGLDRAWELEMENTSINSTANCEDANGLEPROC) (
+        GLenum mode, GLsizei count, GLenum type, const void* indices,
+        GLsizei primcount);
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY glVertexAttribDivisorANGLE(
+    GLuint index, GLuint divisor);
+#endif
+typedef void (
+    GL_APIENTRYP PFNGLVERTEXATTRIBDIVISORANGLEPROC) (
+        GLuint index, GLuint divisor);
+#endif  /* GL_ANGLE_instanced_arrays */
+
 /* GL_CHROMIUM_texture_compression_dxt5 */
 #ifndef GL_CHROMIUM_texture_compression_dxt5
 #define GL_CHROMIUM_texture_compression_dxt5 1