gpu: Use decoder state restoration for scoped_binders

gpu/command_buffer/service/context_state.cc

Index: gpu/command_buffer/service/context_state.cc
diff --git a/gpu/command_buffer/service/context_state.cc b/gpu/command_buffer/service/context_state.cc
index 5aa24fbacd095e7c09ea022d30254b49588ba9fe..7259d753b628349c4598f445b835408592d50610 100644
--- a/gpu/command_buffer/service/context_state.cc
+++ b/gpu/command_buffer/service/context_state.cc
@@ -77,6 +77,16 @@ bool TargetIsSupported(const FeatureInfo* feature_info, GLuint target) {
   }
 }
 
+bool BufferTargetIsSupported(GLuint target) {
+  switch (target) {
+    case GL_ARRAY_BUFFER:
+      return true;
+    default:
+      NOTREACHED();
+      return false;
+  }
+}
+
 GLuint GetBufferId(const Buffer* buffer) {
   if (buffer)
     return buffer->service_id();
@@ -306,6 +316,11 @@ void ContextState::DoLineWidth(GLfloat width) const {
       std::min(std::max(width, line_width_min_), line_width_max_));
 }
 
+void ContextState::RestoreBufferBinding(unsigned int target) const {
+  if (BufferTargetIsSupported(target))

[piman, 2017/03/30 18:31:43]

Why this logic? Other targets *are* supported at the context level. It would be
extremely surprising for users to use a ScopedBufferBinder to not work based on
the target

[Chandan, 2017/03/30 19:22:39]

I added this logic to keep it consistent with !state_restorer_ case in
ScopedBufferBinder ctor.
So, target will be passed on to glBindBuffer without any check?

+    glBindBuffer(target, GetBufferId(bound_array_buffer.get()));
+}
+
 void ContextState::RestoreBufferBindings() const {
   if (vertex_attrib_manager.get()) {
     Buffer* element_array_buffer =