aw: Avoid leaking GL error across android and chromium

android_webview/browser/scoped_app_gl_state_restore.cc

 // Copyright 2013 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 "android_webview/browser/scoped_app_gl_state_restore.h"
 
 #include <string>
 
 #include "base/debug/trace_event.h"
 #include "base/lazy_instance.h"
@@ skipping 130 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ScopedAppGLStateRestoreImpl);
 };
 
 ScopedAppGLStateRestoreImpl::ScopedAppGLStateRestoreImpl(
     ScopedAppGLStateRestore::CallMode mode)
     : mode_(mode) {
   TRACE_EVENT0("android_webview", "AppGLStateSave");
   MakeAppContextCurrent();
 
+  // Ignore incoming GL errors.
+  GLenum error = glGetError();
+  DLOG_IF(WARNING, error != static_cast<GLenum>(GL_NO_ERROR))
+      << "Incoming GLError " << error;

[no sievers, 2014/05/15 20:49:24]

Since it's an error stack you need to loop over it, see
ErrorStateImpl::ClearRealGLErrors() in error_state.cc

+
   if (!g_globals_initialized) {
     g_globals_initialized = true;
 
     glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &g_gl_max_texture_units);
     DCHECK_GT(g_gl_max_texture_units, 0);
 
     std::string extensions(
         reinterpret_cast<const char*>(glGetString(GL_EXTENSIONS)));
     g_supports_oes_vertex_array_object =
         extensions.find("GL_OES_vertex_array_object") != std::string::npos;
@@ skipping 83 matching lines @@
     glGetVertexAttribPointerv(
         i, GL_VERTEX_ATTRIB_ARRAY_POINTER, &vertex_attrib_[i].pointer);
     glGetVertexAttribPointerv(
         i, GL_VERTEX_ATTRIB_ARRAY_POINTER, &vertex_attrib_[i].pointer);
     glGetVertexAttribiv(i,
                         GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING,
                         &vertex_attrib_[i].vertex_attrib_array_buffer_binding);
     glGetVertexAttribfv(
         i, GL_CURRENT_VERTEX_ATTRIB, vertex_attrib_[i].current_vertex_attrib);
   }
+  DCHECK_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR));
 }
 
 ScopedAppGLStateRestoreImpl::~ScopedAppGLStateRestoreImpl() {
   TRACE_EVENT0("android_webview", "AppGLStateRestore");
   MakeAppContextCurrent();
 
+  DCHECK_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR));
+
   glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer_binding_ext_);
   glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_array_buffer_binding_);
 
   if (g_supports_oes_vertex_array_object)
     glBindVertexArrayOES(0);
 
   for (size_t i = 0; i < ARRAYSIZE_UNSAFE(vertex_attrib_); ++i) {
     glBindBuffer(GL_ARRAY_BUFFER,
                  vertex_attrib_[i].vertex_attrib_array_buffer_binding);
     glVertexAttribPointer(i,
@@ skipping 70 matching lines @@
 
       GLEnableDisable(GL_SCISSOR_TEST, scissor_test_);
 
       glScissor(
           scissor_box_[0], scissor_box_[1], scissor_box_[2], scissor_box_[3]);
       break;
   }
 
   GLEnableDisable(GL_STENCIL_TEST, stencil_test_);
   glStencilFunc(stencil_func_, stencil_mask_, stencil_ref_);
+
+  // Do not leak GLError out of chromium.
+  GLenum error = glGetError();
+  DLOG_IF(WARNING, error != static_cast<GLenum>(GL_NO_ERROR))
+      << "Chromium produced GLError " << error;
 }
 
 }  // namespace internal
 
 ScopedAppGLStateRestore::ScopedAppGLStateRestore(CallMode mode)
     : impl_(new internal::ScopedAppGLStateRestoreImpl(mode)) {
 }
 
 ScopedAppGLStateRestore::~ScopedAppGLStateRestore() {}
 
 bool ScopedAppGLStateRestore::stencil_enabled() const {
   return impl_->stencil_enabled();
 }
 int ScopedAppGLStateRestore::framebuffer_binding_ext() const {
   return impl_->framebuffer_binding_ext();
 }
 
 }  // namespace android_webview