Add an extension for querying esimated GPU memory size of resources.

BUG=892288

Change-Id: I56fc3ab00c06d711e1a21eb1ad4b2224126730dc
Reviewed-on: https://chromium-review.googlesource.com/c/1262021
Reviewed-by: Yuly Novikov <ynovikov@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES31.cpp b/src/libANGLE/validationES31.cpp
index a2561bd..4ec51b2 100644
--- a/src/libANGLE/validationES31.cpp
+++ b/src/libANGLE/validationES31.cpp
@@ -954,6 +954,14 @@
             break;
         case GL_TEXTURE_COMPRESSED:
             break;
+        case GL_MEMORY_SIZE_ANGLE:
+            if (!context->getExtensions().memorySize)
+            {
+                ANGLE_VALIDATION_ERR(context, InvalidEnum(), ExtensionNotEnabled);
+                return false;
+            }
+            break;
+
         default:
             ANGLE_VALIDATION_ERR(context, InvalidEnum(), InvalidPname);
             return false;