Fix the crash problem of WebGL2 Query api.

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.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 "modules/webgl/WebGL2RenderingContextBase.h"
 
 #include "bindings/modules/v8/WebGLAny.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLImageElement.h"
@@ skipping 1575 matching lines @@
 {
     if (isContextLost())
         return nullptr;
     WebGLQuery* o = WebGLQuery::create(this);
     addSharedObject(o);
     return o;
 }
 
 void WebGL2RenderingContextBase::deleteQuery(WebGLQuery* query)
 {
+    if (!query) {
+        synthesizeGLError(GL_INVALID_OPERATION, "deleteQuery", "query object is null");

[Zhenyao Mo, 2015/11/25 18:16:33]

You should follow the same pattern from other delete functions, say,
WebGLRenderingContextBase::deleteTexture().  No GL error needed.

+        return;
+    }
+
     if (m_currentBooleanOcclusionQuery == query) {
         webContext()->endQueryEXT(m_currentBooleanOcclusionQuery->getTarget());
         m_currentBooleanOcclusionQuery = nullptr;
     }
 
     if (m_currentTransformFeedbackPrimitivesWrittenQuery == query) {
         webContext()->endQueryEXT(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
         m_currentTransformFeedbackPrimitivesWrittenQuery = nullptr;
     }
 
     deleteObject(query);
 }
 
 GLboolean WebGL2RenderingContextBase::isQuery(WebGLQuery* query)
 {
     if (isContextLost() || !query)
         return 0;
 
     return webContext()->isQueryEXT(query->object());
 }
 
 void WebGL2RenderingContextBase::beginQuery(GLenum target, WebGLQuery* query)
 {
     bool deleted;
+    if (!query) {
+        synthesizeGLError(GL_INVALID_OPERATION, "beginQuery", "query object is null");
+        return;
+    }
+
     if (!checkObjectToBeBound("beginQuery", query, deleted))
         return;
     if (deleted) {
         synthesizeGLError(GL_INVALID_OPERATION, "beginQuery", "attempted to begin a deleted query object");
         return;
     }
 
     if (query->getTarget() && query->getTarget() != target) {
         synthesizeGLError(GL_INVALID_OPERATION, "beginQuery", "query type does not match target");
         return;
@@ skipping 1581 matching lines @@
 GLenum WebGL2RenderingContextBase::boundFramebufferColorFormat()
 {
     if (m_readFramebufferBinding && m_readFramebufferBinding->object())
         return m_readFramebufferBinding->colorBufferFormat();
     if (m_requestedAttributes.alpha())
         return GL_RGBA;
     return GL_RGB;
 }
 
 } // namespace blink