Load the GL_ANGLE_robust_client_memory entry points.

BUG=angleproject:1354

Review-Url: https://codereview.chromium.org/2385323003
Cr-Commit-Position: refs/heads/master@{#423032}

ui/gl/gl_mock.h

@@ -57,6 +57,20 @@ class MockGLInterface {
     NOTREACHED();
   }
 
+  void TexImage3DRobustANGLE(GLenum target,
+                             GLint level,
+                             GLint internalformat,
+                             GLsizei width,
+                             GLsizei height,
+                             GLsizei depth,
+                             GLint border,
+                             GLenum format,
+                             GLenum type,
+                             GLsizei bufSize,
+                             const void* pixels) {
+    NOTREACHED();
+  }
+
   void TexSubImage3D(
       GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint zoffset,
       GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type,
@@ -69,6 +83,21 @@ class MockGLInterface {
     }
   }
 
+  void TexSubImage3DRobustANGLE(GLenum target,
+                                GLint level,
+                                GLint xoffset,
+                                GLint yoffset,
+                                GLint zoffset,
+                                GLsizei width,
+                                GLsizei height,
+                                GLsizei depth,
+                                GLenum format,
+                                GLenum type,
+                                GLsizei bufSize,
+                                const void* pixels) {
+    NOTREACHED();
+  }
+
   MOCK_METHOD10(TexSubImage3DNoData,
                 void(GLenum target,
                      GLint level,