Enforce queries' new availability semantics.

third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp b/third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp
index a3a7ab940d4bd9de6a6ac6f5ab36c469ae0f3fb0..74210c35738ac2c759cc92ce4a5deca4f71525af 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLQuery.cpp
@@ -7,6 +7,7 @@
 #include "modules/webgl/WebGLQuery.h"
 
 #include "modules/webgl/WebGL2RenderingContextBase.h"
+#include "public/platform/Platform.h"
 
 namespace blink {
 
@@ -17,6 +18,8 @@ WebGLQuery* WebGLQuery::create(WebGL2RenderingContextBase* ctx)
 
 WebGLQuery::~WebGLQuery()
 {
+    unregisterTaskObserver();
+
     // See the comment in WebGLObject::detachAndDeleteObject().
     detachAndDeleteObject();
 }
@@ -24,6 +27,10 @@ WebGLQuery::~WebGLQuery()
 WebGLQuery::WebGLQuery(WebGL2RenderingContextBase* ctx)
     : WebGLSharedPlatform3DObject(ctx)
     , m_target(0)
+    , m_taskObserverRegistered(false)
+    , m_canUpdateAvailability(false)
+    , m_queryResultAvailable(false)
+    , m_queryResult(0)
 {
     setObject(ctx->webContext()->createQueryEXT());
 }
@@ -41,4 +48,70 @@ void WebGLQuery::deleteObjectImpl(WebGraphicsContext3D* context3d)
     m_object = 0;
 }
 
+void WebGLQuery::resetCachedResult()
+{
+    m_canUpdateAvailability = false;
+    m_queryResultAvailable = false;
+    m_queryResult = 0;
+    // When this is called, the implication is that we should start
+    // keeping track of whether we can update the cached availability
+    // and result.
+    registerTaskObserver();
+}
+
+void WebGLQuery::updateCachedResult(WebGraphicsContext3D* ctx)
+{
+    if (m_queryResultAvailable)
+        return;
+
+    if (!m_canUpdateAvailability)
+        return;
+
+    if (!hasTarget())
+        return;
+
+    // We can only update the cached result when control returns to the browser.
+    m_canUpdateAvailability = false;
+    GLuint available = 0;
+    ctx->getQueryObjectuivEXT(object(), GL_QUERY_RESULT_AVAILABLE_EXT, &available);
+    m_queryResultAvailable = !!available;
+    if (m_queryResultAvailable) {
+        GLuint result = 0;
+        ctx->getQueryObjectuivEXT(object(), GL_QUERY_RESULT_EXT, &result);
+        m_queryResult = result;
+        unregisterTaskObserver();
+    }
+}
+
+bool WebGLQuery::isQueryResultAvailable()
+{
+    return m_queryResultAvailable;
+}
+
+GLuint WebGLQuery::getQueryResult()
+{
+    return m_queryResult;
+}
+
+void WebGLQuery::registerTaskObserver()
+{
+    if (!m_taskObserverRegistered) {
+        m_taskObserverRegistered = true;
+        Platform::current()->currentThread()->addTaskObserver(this);
+    }
+}
+
+void WebGLQuery::unregisterTaskObserver()
+{
+    if (m_taskObserverRegistered) {
+        m_taskObserverRegistered = false;
+        Platform::current()->currentThread()->removeTaskObserver(this);
+    }
+}
+
+void WebGLQuery::didProcessTask()
+{
+    m_canUpdateAvailability = true;
+}
+
 } // namespace blink