Improving support for WebGL2 Query objects

Source/core/html/canvas/WebGLQuery.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "core/html/canvas/WebGLQuery.h"
 
 #include "core/html/canvas/WebGL2RenderingContextBase.h"
 
@@ skipping 11 matching lines @@
     // with or without Oilpan enabled.
     //
     // See comment in WebGLBuffer's destructor for additional
     // information on why this is done for WebGLSharedObject-derived
     // objects.
     detachAndDeleteObject();
 }
 
 WebGLQuery::WebGLQuery(WebGL2RenderingContextBase* ctx)
     : WebGLSharedPlatform3DObject(ctx)
+    , m_target(0)
 {
     setObject(ctx->webContext()->createQueryEXT());
 }
 
+void WebGLQuery::setTarget(GLenum target)
+{
+    if (!object() || !compatibleTarget(target))
+        return;

[Ken Russell (switch to Gerrit), 2015/06/24 21:07:22]

These checks are supposed to be validated by the caller, so rather than silently
short-circuiting, I think these should be added as ASSERTs.

+
+    m_target = target;
+}
+
+bool WebGLQuery::compatibleTarget(GLenum target)
+{
+    if (!m_target)
+        return true;
+
+    switch (target) {
+    // The SAMPLES_PASSED targets are interchangable.
+    case GL_ANY_SAMPLES_PASSED:
+    case GL_ANY_SAMPLES_PASSED_CONSERVATIVE:
+        return m_target == GL_ANY_SAMPLES_PASSED || m_target == GL_ANY_SAMPLES_PASSED_CONSERVATIVE;
+    // Otherwise target is finalized the first time beginQuery() is called.
+    default:
+        return m_target == target;
+    }
+}
+
 void WebGLQuery::deleteObjectImpl(WebGraphicsContext3D* context3d)
 {
     context3d->deleteQueryEXT(m_object);
     m_object = 0;
 }
 
 } // namespace blink