Add reference-counting for mailbox textures.

gpu/command_buffer/service/texture_manager.cc

Index: gpu/command_buffer/service/texture_manager.cc
diff --git a/gpu/command_buffer/service/texture_manager.cc b/gpu/command_buffer/service/texture_manager.cc
index b1bbe1242d4dd1ceeb344d81e24324a077ae0da8..f4bf8e24d10eef6ed00da81fdd22cc1fd0a5bcac 100644
--- a/gpu/command_buffer/service/texture_manager.cc
+++ b/gpu/command_buffer/service/texture_manager.cc
@@ -10,7 +10,6 @@
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "gpu/command_buffer/service/mailbox_manager.h"
 #include "gpu/command_buffer/service/memory_tracking.h"
-#include "gpu/command_buffer/service/texture_definition.h"
 
 namespace gpu {
 namespace gles2 {
@@ -108,13 +107,20 @@ Texture::Texture(TextureManager* manager, GLuint service_id)
       owned_(true),
       stream_texture_(false),
       immutable_(false),
-      estimated_size_(0) {
+      estimated_size_(0),
+      shared_texture_(NULL) {
   if (manager_) {
     manager_->StartTracking(this);
   }
 }
 
 Texture::~Texture() {
+  if (shared_texture_) {
+    bool have_context = manager_ && manager_->have_context_;
+    owned_ = shared_texture_->service_id() != service_id();
+    StopUsingSharedTexture(have_context);
+  }
+
   if (manager_) {
     if (owned_ && manager_->have_context_) {
       GLuint id = service_id();
@@ -694,6 +700,19 @@ gfx::GLImage* Texture::GetLevelImage(
   return 0;
 }
 
+
+void Texture::StartUsingSharedTexture(TextureDefinition* definition) {
+  shared_texture_ = definition;
+  TextureDefinition::Client::StartUsingSharedTexture(definition);
+}
+
+bool Texture::StopUsingSharedTexture(bool have_context) {
+  bool was_deleted = TextureDefinition::Client::StopUsingSharedTexture(
+      shared_texture_, have_context);
+  shared_texture_ = NULL;
+  return was_deleted;
+}
+
 TextureManager::TextureManager(
     MemoryTracker* memory_tracker,
     FeatureInfo* feature_info,
@@ -933,6 +952,11 @@ void TextureManager::SetLevelInfo(
 TextureDefinition* TextureManager::Save(Texture* texture) {
   DCHECK(texture->owned_);
 
+  // Fail if we are not the current owner of the shared texture.
+  if (texture->shared_texture_ &&
+      texture->shared_texture_->service_id() != texture->service_id())
+    return NULL;
+
   if (texture->IsAttachedToFramebuffer())
     return NULL;
 
@@ -976,17 +1000,21 @@ TextureDefinition* TextureManager::Save(Texture* texture) {
   GLuint new_service_id = 0;
   glGenTextures(1, &new_service_id);
   texture->SetServiceId(new_service_id);
-  texture->SetImmutable(false);
-
-  return new TextureDefinition(texture->target(),
-                               old_service_id,
-                               texture->min_filter(),
-                               texture->mag_filter(),
-                               texture->wrap_s(),
-                               texture->wrap_t(),
-                               texture->usage(),
-                               immutable,
-                               level_infos);
+  texture->SetImmutable(true);
+
+  if (!texture->shared_texture_) {
+    texture->StartUsingSharedTexture(
+        new TextureDefinition(texture->target(),
+                              old_service_id,
+                              texture->min_filter(),
+                              texture->mag_filter(),
+                              texture->wrap_s(),
+                              texture->wrap_t(),
+                              texture->usage(),
+                              immutable,
+                              level_infos));
+  }
+  return texture->shared_texture_;
 }
 
 bool TextureManager::Restore(
@@ -996,8 +1024,6 @@ bool TextureManager::Restore(
     TextureDefinition* definition) {
   DCHECK(texture->owned_);
 
-  scoped_ptr<TextureDefinition> scoped_definition(definition);
-
   if (texture->IsAttachedToFramebuffer())
     return false;
 
@@ -1036,8 +1062,26 @@ bool TextureManager::Restore(
   }
 
   GLuint old_service_id = texture->service_id();
-  glDeleteTextures(1, &old_service_id);
-  texture->SetServiceId(definition->ReleaseServiceId());
+
+  // We don't allow real sharing (yet), so we can't already be using the same
+  // texture.
+  DCHECK(definition->service_id() != old_service_id);
+
+  if (texture->shared_texture_ && texture->shared_texture_ != definition) {
+    // We were already referencing a texture, and it's different from the one we
+    // are consuming now.
+    bool owned = texture->shared_texture_->service_id() != old_service_id;
+    if (owned)
+      glDeleteTextures(1, &old_service_id);
+    texture->StopUsingSharedTexture(true);
+  } else {
+    glDeleteTextures(1, &old_service_id);
+  }
+
+  if (!texture->shared_texture_)
+    texture->StartUsingSharedTexture(definition);
+
+  texture->SetServiceId(definition->service_id());
   glBindTexture(texture->target(), texture->service_id());
   texture->SetImmutable(definition->immutable());
   SetParameter(function_name, decoder, texture, GL_TEXTURE_MIN_FILTER,