Restore only modified texture state during virtual context switches

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 e8912cfe1625b769dc0047b935c2f098aed31da3..654c1d4137948aee967cac727639e238bb8e05fb 100644
--- a/gpu/command_buffer/service/context_state.cc
+++ b/gpu/command_buffer/service/context_state.cc
@@ -10,6 +10,7 @@
 #include "gpu/command_buffer/service/framebuffer_manager.h"
 #include "gpu/command_buffer/service/program_manager.h"
 #include "gpu/command_buffer/service/renderbuffer_manager.h"
+#include "ui/gl/dirty_texture_state.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_implementation.h"
 
@@ -47,30 +48,44 @@ ContextState::ContextState(FeatureInfo* feature_info, Logger* logger)
 ContextState::~ContextState() {
 }
 
-void ContextState::RestoreTextureUnitBindings(GLuint unit) const {
+void ContextState::RestoreTextureUnitBindings(
+    GLuint unit, const gfx::DirtyTextureState* dirty_texture_state) const {
   DCHECK_LT(unit, texture_units.size());
   const TextureUnit& texture_unit = texture_units[unit];
   glActiveTexture(GL_TEXTURE0 + unit);
-  GLuint service_id = texture_unit.bound_texture_2d.get()
-                          ? texture_unit.bound_texture_2d->service_id()
-                          : 0;
-  glBindTexture(GL_TEXTURE_2D, service_id);
-  service_id = texture_unit.bound_texture_cube_map.get()
-                   ? texture_unit.bound_texture_cube_map->service_id()
-                   : 0;
-  glBindTexture(GL_TEXTURE_CUBE_MAP, service_id);
-
-  if (feature_info_->feature_flags().oes_egl_image_external) {
-    service_id = texture_unit.bound_texture_external_oes.get()
-                     ? texture_unit.bound_texture_external_oes->service_id()
-                     : 0;
+  if (!dirty_texture_state ||
+      dirty_texture_state->IsBinding2DDirtyForUnit(unit)) {
+    GLuint service_id = texture_unit.bound_texture_2d.get()
+                            ? texture_unit.bound_texture_2d->service_id()
+                            : 0;
+    glBindTexture(GL_TEXTURE_2D, service_id);
+  }
+
+  if (!dirty_texture_state ||
+      dirty_texture_state->IsBindingCubeMapDirtyForUnit(unit)) {
+    GLuint service_id = texture_unit.bound_texture_cube_map.get()
+                            ? texture_unit.bound_texture_cube_map->service_id()
+                            : 0;
+    glBindTexture(GL_TEXTURE_CUBE_MAP, service_id);
+  }
+
+  if (feature_info_->feature_flags().oes_egl_image_external &&
+      (!dirty_texture_state ||
+       dirty_texture_state->IsBindingExternalOesDirtyForUnit(unit))) {
+    GLuint service_id =
+        texture_unit.bound_texture_external_oes.get()
+            ? texture_unit.bound_texture_external_oes->service_id()
+            : 0;
     glBindTexture(GL_TEXTURE_EXTERNAL_OES, service_id);
   }
 
-  if (feature_info_->feature_flags().arb_texture_rectangle) {
-    service_id = texture_unit.bound_texture_rectangle_arb.get()
-                     ? texture_unit.bound_texture_rectangle_arb->service_id()
-                     : 0;
+  if (feature_info_->feature_flags().arb_texture_rectangle &&
+      (!dirty_texture_state ||
+       dirty_texture_state->IsBindingRectangleArbDirtyForUnit(unit))) {
+    GLuint service_id =
+        texture_unit.bound_texture_rectangle_arb.get()
+            ? texture_unit.bound_texture_rectangle_arb->service_id()
+            : 0;
     glBindTexture(GL_TEXTURE_RECTANGLE_ARB, service_id);
   }
 }
@@ -101,10 +116,15 @@ void ContextState::RestoreActiveTexture() const {
   glActiveTexture(GL_TEXTURE0 + active_texture_unit);
 }
 
-void ContextState::RestoreAllTextureUnitBindings() const {
+void ContextState::RestoreAllTextureUnitBindings(
+    const gfx::DirtyTextureState* dirty_texture_state) const {
+  size_t texture_units_to_restore =
+      dirty_texture_state ?
+          dirty_texture_state->GetMaxTextureUnitIndex() + 1
+              : texture_units.size();
   // Restore Texture state.
-  for (size_t ii = 0; ii < texture_units.size(); ++ii) {
-    RestoreTextureUnitBindings(ii);
+  for (size_t ii = 0; ii < texture_units_to_restore; ++ii) {
+    RestoreTextureUnitBindings(ii, dirty_texture_state);
   }
   RestoreActiveTexture();
 }
@@ -139,8 +159,9 @@ void ContextState::RestoreGlobalState() const {
   InitState();
 }
 
-void ContextState::RestoreState() const {
-  RestoreAllTextureUnitBindings();
+void ContextState::RestoreState(
+    const gfx::DirtyTextureState* dirty_texture_state) const {
+  RestoreAllTextureUnitBindings(dirty_texture_state);
 
   // Restore Attrib State
   // TODO: This if should not be needed. RestoreState is getting called