Add tokens and entry points for KHR_blend_equation_advanced

src/gpu/gl/GrGLInterface.cpp

Index: src/gpu/gl/GrGLInterface.cpp
diff --git a/src/gpu/gl/GrGLInterface.cpp b/src/gpu/gl/GrGLInterface.cpp
index dba005976f366251f2c7e8177a67fb55303d1654..afb6c7c5531c78e684402b5fec119096a23b4a49 100644
--- a/src/gpu/gl/GrGLInterface.cpp
+++ b/src/gpu/gl/GrGLInterface.cpp
@@ -114,8 +114,9 @@ bool GrGLInterface::validate() const {
         NULL == fFunctions.fBindAttribLocation ||
         NULL == fFunctions.fBindBuffer ||
         NULL == fFunctions.fBindTexture ||
+        NULL == fFunctions.fBlendColor ||      // -> GL >= 1.4 or extension, ES >= 2.0
+        NULL == fFunctions.fBlendEquation ||   // -> GL >= 1.4 or extension, ES >= 2.0
         NULL == fFunctions.fBlendFunc ||
-        NULL == fFunctions.fBlendColor ||      // -> GL >= 1.4, ES >= 2.0 or extension
         NULL == fFunctions.fBufferData ||
         NULL == fFunctions.fBufferSubData ||
         NULL == fFunctions.fClear ||
@@ -306,6 +307,12 @@ bool GrGLInterface::validate() const {
         }
     }
 
+    if (fExtensions.has("GL_KHR_blend_equation_advanced")) {
+        if (NULL == fFunctions.fBlendBarrier) {
+            RETURN_FALSE_INTERFACE
+        }
+    }
+
     if (fExtensions.has("GL_EXT_discard_framebuffer")) {
 // FIXME: Remove this once Chromium is updated to provide this function
 #if 0