Restore only modified texture state during virtual context switches

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 eade3cedaf5e6df54041372b964335aa7937edca..01723b3d9c98565fb3a77a2767d585c89acfed91 100644
--- a/ui/gl/gl_gl_api_implementation.cc
+++ b/ui/gl/gl_gl_api_implementation.cc
@@ -254,7 +254,8 @@ TraceGLApi::~TraceGLApi() {
 
 VirtualGLApi::VirtualGLApi()
     : real_context_(NULL),
-      current_context_(NULL) {
+      current_context_(NULL),
+      current_active_texture_unit_(GL_TEXTURE0) {
 }
 
 VirtualGLApi::~VirtualGLApi() {
@@ -306,15 +307,15 @@ bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
     DCHECK_EQ(glGetErrorFn(), static_cast<GLenum>(GL_NO_ERROR));
 
     current_context_ = virtual_context;
-    // Set all state that is different from the real state
-    // NOTE: !!! This is a temporary implementation that just restores all
-    // state to let us test that it works.
-    // TODO: ASAP, change this to something that only restores the state
-    // needed for individual GL calls.
+    // Set all state that is different from the real state.
     GLApi* temp = GetCurrentGLApi();
     SetGLToRealGLApi();
-    if (virtual_context->GetGLStateRestorer()->IsInitialized())
-      virtual_context->GetGLStateRestorer()->RestoreState();
+    if (virtual_context->GetGLStateRestorer()->IsInitialized()) {
+      virtual_context->GetGLStateRestorer()->RestoreState(
+          &dirty_texture_state_);
+      // Clear our dirty state after restoring state.
+      ClearDirtyTextureState();
+    }
     SetGLApi(temp);
   }
   SetGLApi(this);
@@ -328,8 +329,10 @@ bool VirtualGLApi::MakeCurrent(GLContext* virtual_context, GLSurface* surface) {
 }
 
 void VirtualGLApi::OnReleaseVirtuallyCurrent(GLContext* virtual_context) {
-  if (current_context_ == virtual_context)
+  if (current_context_ == virtual_context) {
     current_context_ = NULL;
+    ClearDirtyTextureState();
+  }
 }
 
 const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
@@ -341,4 +344,20 @@ const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   }
 }
 
+void VirtualGLApi::glBindTextureFn(GLenum target, GLuint texture_id) {
+  dirty_texture_state_.AddBinding(current_active_texture_unit_, target);
+  driver_->fn.glBindTextureFn(target, texture_id);
+}
+
+void VirtualGLApi::glActiveTextureFn(GLenum texture_unit) {
+  current_active_texture_unit_ = texture_unit;
+  dirty_texture_state_.UpdateMaxTextureUnit(texture_unit);
+  driver_->fn.glActiveTextureFn(texture_unit);
+}
+
+void VirtualGLApi::ClearDirtyTextureState() {
+  current_active_texture_unit_ = GL_TEXTURE0;
+  dirty_texture_state_.Clear();
+}
+
 }  // namespace gfx