[Merge M54] aw: Fix FBO restore in webview functor

android_webview/browser/scoped_app_gl_state_restore.cc

Index: android_webview/browser/scoped_app_gl_state_restore.cc
diff --git a/android_webview/browser/scoped_app_gl_state_restore.cc b/android_webview/browser/scoped_app_gl_state_restore.cc
index da1c5aaa9f1fa5545dde708ddfbe8492a7bfbb4a..15895dd508ec0e8ed382909bf4bfc4f4c2e4d53f 100644
--- a/android_webview/browser/scoped_app_gl_state_restore.cc
+++ b/android_webview/browser/scoped_app_gl_state_restore.cc
@@ -66,6 +66,7 @@ bool ClearGLErrors(bool warn, const char* msg) {
 bool g_globals_initialized = false;
 GLint g_gl_max_texture_units = 0;
 bool g_supports_oes_vertex_array_object = false;
+ScopedAppGLStateRestore* g_current_instance = nullptr;
 
 }  // namespace
 
@@ -416,11 +417,22 @@ ScopedAppGLStateRestoreImpl::~ScopedAppGLStateRestoreImpl() {
 
 }  // namespace internal
 
+// static
+ScopedAppGLStateRestore* ScopedAppGLStateRestore::Current() {
+  DCHECK(g_current_instance);
+  return g_current_instance;
+}
+
 ScopedAppGLStateRestore::ScopedAppGLStateRestore(CallMode mode)
     : impl_(new internal::ScopedAppGLStateRestoreImpl(mode)) {
+  DCHECK(!g_current_instance);
+  g_current_instance = this;
 }
 
-ScopedAppGLStateRestore::~ScopedAppGLStateRestore() {}
+ScopedAppGLStateRestore::~ScopedAppGLStateRestore() {
+  DCHECK_EQ(this, g_current_instance);
+  g_current_instance = nullptr;
+}
 
 StencilState ScopedAppGLStateRestore::stencil_state() const {
   return impl_->stencil_state();