Add validation to the mailbox functions in the passthrough cmd decoder.

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
diff --git a/gpu/command_buffer/service/texture_manager.h b/gpu/command_buffer/service/texture_manager.h
index 11c8b6305050b6bff3fb6abacfa2c52b5bddf6e5..394feefab4501613a9d841a51b4bd36c222eba5b 100644
--- a/gpu/command_buffer/service/texture_manager.h
+++ b/gpu/command_buffer/service/texture_manager.h
@@ -51,10 +51,21 @@ class GPU_EXPORT TextureBase {
   // The service side OpenGL id of the texture.
   GLuint service_id() const { return service_id_; }
 
+  // Returns the target this texure was first bound to or 0 if it has not
+  // been bound. Once a texture is bound to a specific target it can never be
+  // bound to a different target.
+  GLenum target() const { return target_; }
+
  protected:
   // The id of the texture.
   GLuint service_id_;
 
+  // The target. 0 if unset, otherwise GL_TEXTURE_2D or GL_TEXTURE_CUBE_MAP.
+  //             Or GL_TEXTURE_2D_ARRAY or GL_TEXTURE_3D (for GLES3).
+  GLenum target_;
+
+  void SetTarget(GLenum target);
+
   void DeleteFromMailboxManager();
 
  private:
@@ -71,7 +82,7 @@ class GPU_EXPORT TextureBase {
 class TexturePassthrough final : public TextureBase,
                                  public base::RefCounted<TexturePassthrough> {
  public:
-  explicit TexturePassthrough(GLuint service_id);
+  TexturePassthrough(GLuint service_id, GLenum target);
 
   // Notify the texture that the context is lost and it shouldn't delete the
   // native GL texture in the destructor
@@ -195,13 +206,6 @@ class GPU_EXPORT Texture final : public TextureBase {
     owned_service_id_ = service_id;
   }
 
-  // Returns the target this texure was first bound to or 0 if it has not
-  // been bound. Once a texture is bound to a specific target it can never be
-  // bound to a different target.
-  GLenum target() const {
-    return target_;
-  }
-
   bool SafeToRenderFrom() const {
     return cleared_;
   }
@@ -593,10 +597,6 @@ class GPU_EXPORT Texture final : public TextureBase {
   int num_uncleared_mips_;
   int num_npot_faces_;
 
-  // The target. 0 if unset, otherwise GL_TEXTURE_2D or GL_TEXTURE_CUBE_MAP.
-  //             Or GL_TEXTURE_2D_ARRAY or GL_TEXTURE_3D (for GLES3).
-  GLenum target_;
-
   // Texture parameters.
   SamplerState sampler_state_;
   GLenum usage_;