Adds support for the GL_ANGLE_texture_usage and GL_EXT_texture_storage

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
===================================================================
--- gpu/command_buffer/service/texture_manager.h	(revision 112643)
+++ gpu/command_buffer/service/texture_manager.h	(working copy)
@@ -40,6 +40,7 @@
           mag_filter_(GL_LINEAR),
           wrap_s_(GL_REPEAT),
           wrap_t_(GL_REPEAT),
+          usage_(GL_NONE),
           max_level_set_(-1),
           texture_complete_(false),
           cube_complete_(false),
@@ -66,6 +67,10 @@
       return wrap_t_;
     }
 
+    GLenum usage() const {
+      return usage_;
+    }
+
     int num_uncleared_mips() const {
       return num_uncleared_mips_;
     }
@@ -282,6 +287,7 @@
     GLenum mag_filter_;
     GLenum wrap_s_;
     GLenum wrap_t_;
+    GLenum usage_;
 
     // The maximum level that has been set.
     GLint max_level_set_;