Add support for GL texture storage

Review URL: http://codereview.appspot.com/5462046/



git-svn-id: http://skia.googlecode.com/svn/trunk@2966 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGLInterface.cpp b/src/gpu/GrGLInterface.cpp
index d46aaa7..66aea63 100644
--- a/src/gpu/GrGLInterface.cpp
+++ b/src/gpu/GrGLInterface.cpp
@@ -178,6 +178,7 @@
     fStencilOpSeparate = NULL;
     fTexImage2D = NULL;
     fTexParameteri = NULL;
+    fTexStorage2D = NULL;
     fTexSubImage2D = NULL;
     fUniform1f = NULL;
     fUniform1i = NULL;
@@ -416,6 +417,14 @@
         return false;
     }
 
+    // GL_EXT_texture_storage is part of desktop 4.2
+    // There is a desktop ARB extension and an ES+desktop EXT extension
+    if ((kDesktop_GrGLBinding == fBindingsExported &&
+         (glVer >= GR_GL_VER(4,2)) ||
+          GrGLHasExtensionFromString("GL_ARB_texture_storage", ext)) ||
+        GrGLHasExtensionFromString("GL_EXT_texture_storage", ext)) {
+    }
+
     // FBO MSAA
     if (kDesktop_GrGLBinding == fBindingsExported) {
         // GL 3.0 and the ARB extension have multisample + blit