gpu: Allow fences to check whether a flush has occurred

ui/gl/gl_gl_api_implementation.cc

Index: ui/gl/gl_gl_api_implementation.cc
diff --git a/ui/gl/gl_gl_api_implementation.cc b/ui/gl/gl_gl_api_implementation.cc
index f925f64ffa88af185c41ca880c09a484e094706d..0965d91b45dab518fd9a0c34778e1817e3fa2f96 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -343,6 +343,11 @@ void GLApiBase::InitializeBase(DriverGL* driver) {
   driver_ = driver;
 }
 
+void GLApiBase::SignalFlush() {
+  DCHECK(GLContext::GetCurrent());
+  GLContext::GetCurrent()->OnFlush();
+}
+
 RealGLApi::RealGLApi() {
 }
 
@@ -353,6 +358,16 @@ void RealGLApi::Initialize(DriverGL* driver) {
   InitializeBase(driver);
 }
 
+void RealGLApi::glFlushFn() {
+  GLApiBase::glFlushFn();
+  GLApiBase::SignalFlush();
+}
+
+void RealGLApi::glFinishFn() {
+  GLApiBase::glFinishFn();
+  GLApiBase::SignalFlush();
+}
+
 TraceGLApi::~TraceGLApi() {
 }
 
@@ -445,4 +460,14 @@ const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   }
 }
 
+void VirtualGLApi::glFlushFn() {
+  GLApiBase::glFlushFn();
+  GLApiBase::SignalFlush();
+}
+
+void VirtualGLApi::glFinishFn() {
+  GLApiBase::glFinishFn();
+  GLApiBase::SignalFlush();
+}
+
 }  // namespace gfx