diff --git a/gpu/include/GrGLInterface.h b/gpu/include/GrGLInterface.h
index 63ebca5..0e0c566 100644
--- a/gpu/include/GrGLInterface.h
+++ b/gpu/include/GrGLInterface.h
@@ -136,6 +136,7 @@
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLMatrixModeProc)(GrGLenum mode);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLPixelStoreiProc)(GrGLenum pname, GrGLint param);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLPointSizeProc)(GrGLfloat size);
+    typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLReadBufferProc)(GrGLenum src);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLReadPixelsProc)(GrGLint x, GrGLint y, GrGLsizei width, GrGLsizei height, GrGLenum format, GrGLenum type, GrGLvoid* pixels);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLScissorProc)(GrGLint x, GrGLint y, GrGLsizei width, GrGLsizei height);
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLShadeModelProc)(GrGLenum mode);
@@ -291,6 +292,7 @@
     GrGLMatrixModeProc fMatrixMode;
     GrGLPixelStoreiProc fPixelStorei;
     GrGLPointSizeProc fPointSize;
+    GrGLReadBufferProc fReadBuffer;
     GrGLReadPixelsProc fReadPixels;
     GrGLScissorProc fScissor;
     GrGLShadeModelProc fShadeModel;
diff --git a/gpu/src/GrGLInterface.cpp b/gpu/src/GrGLInterface.cpp
index 9822dcb..2a8ffaa 100644
--- a/gpu/src/GrGLInterface.cpp
+++ b/gpu/src/GrGLInterface.cpp
@@ -313,7 +313,8 @@
     if (kDesktop_GrGLBinding == fBindingsExported &&
         (NULL == fLineWidth ||
          NULL == fGetTexLevelParameteriv ||
-         NULL == fDrawBuffer)) {
+         NULL == fDrawBuffer ||
+         NULL == fReadBuffer)) {
         return false;
     }
 
diff --git a/gpu/src/android/GrGLDefaultInterface_android.cpp b/gpu/src/android/GrGLDefaultInterface_android.cpp
index b402176..033a93c 100644
--- a/gpu/src/android/GrGLDefaultInterface_android.cpp
+++ b/gpu/src/android/GrGLDefaultInterface_android.cpp
@@ -77,6 +77,7 @@
     NULL,  // glMatrixMode
     glPixelStorei,
     NULL,  // glPointSize
+    NULL, // glReadBuffer
     glReadPixels,
     glScissor,
     NULL,  // glShadeModel
diff --git a/gpu/src/ios/GrGLDefaultInterface_iOS.cpp b/gpu/src/ios/GrGLDefaultInterface_iOS.cpp
index 8bc9fc5..7bdbcc7 100644
--- a/gpu/src/ios/GrGLDefaultInterface_iOS.cpp
+++ b/gpu/src/ios/GrGLDefaultInterface_iOS.cpp
@@ -76,6 +76,7 @@
         gDefaultInterface.fMatrixMode = glMatrixMode;
         gDefaultInterface.fPointSize = glPointSize;
         gDefaultInterface.fPixelStorei = glPixelStorei;
+        gDefaultInterface.fReadBuffer = NULL; 
         gDefaultInterface.fReadPixels = glReadPixels;
         gDefaultInterface.fScissor = glScissor;
         gDefaultInterface.fShadeModel = glShadeModel;
diff --git a/gpu/src/mac/GrGLDefaultInterface_mac.cpp b/gpu/src/mac/GrGLDefaultInterface_mac.cpp
index 16d2938..293f14c 100644
--- a/gpu/src/mac/GrGLDefaultInterface_mac.cpp
+++ b/gpu/src/mac/GrGLDefaultInterface_mac.cpp
@@ -77,6 +77,7 @@
         gDefaultInterface.fMatrixMode = glMatrixMode;
         gDefaultInterface.fPointSize = glPointSize;
         gDefaultInterface.fPixelStorei = glPixelStorei;
+        gDefaultInterface.fReadBuffer = glReadBuffer;
         gDefaultInterface.fReadPixels = glReadPixels;
         gDefaultInterface.fScissor = glScissor;
         gDefaultInterface.fShadeModel = glShadeModel;
diff --git a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
index 56f2cf7..c6be2df 100644
--- a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
+++ b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
@@ -91,6 +91,7 @@
         gDefaultInterface.fMatrixMode = glMatrixMode;
         gDefaultInterface.fPointSize = glPointSize;
         gDefaultInterface.fPixelStorei = glPixelStorei;
+        gDefaultInterface.fReadBuffer = glReadBuffer;
         gDefaultInterface.fReadPixels = glReadPixels;
         gDefaultInterface.fScissor = glScissor;
         gDefaultInterface.fShadeModel = glShadeModel;
diff --git a/gpu/src/unix/GrGLDefaultInterface_unix.cpp b/gpu/src/unix/GrGLDefaultInterface_unix.cpp
index e38a76b..01725b9 100644
--- a/gpu/src/unix/GrGLDefaultInterface_unix.cpp
+++ b/gpu/src/unix/GrGLDefaultInterface_unix.cpp
@@ -93,6 +93,7 @@
         gDefaultInterface.fMatrixMode = glMatrixMode;
         gDefaultInterface.fPointSize = glPointSize;
         gDefaultInterface.fPixelStorei = glPixelStorei;
+        gDefaultInterface.fReadBuffer = glReadBuffer;
         gDefaultInterface.fReadPixels = glReadPixels;
         gDefaultInterface.fScissor = glScissor;
         gDefaultInterface.fShadeModel = glShadeModel;
diff --git a/gpu/src/win/GrGLDefaultInterface_win.cpp b/gpu/src/win/GrGLDefaultInterface_win.cpp
index 05f5414..1bf0457 100644
--- a/gpu/src/win/GrGLDefaultInterface_win.cpp
+++ b/gpu/src/win/GrGLDefaultInterface_win.cpp
@@ -72,6 +72,7 @@
             gDefaultInterface.fMatrixMode = glMatrixMode;
             gDefaultInterface.fPixelStorei = glPixelStorei;
             gDefaultInterface.fPointSize = glPointSize;
+            gDefaultInterface.fReadBuffer = glReadBuffer;
             gDefaultInterface.fReadPixels = glReadPixels;
             gDefaultInterface.fScissor = glScissor;
             gDefaultInterface.fShadeModel = glShadeModel;