Ensure GL initialization only happens once, and provide common init path

cc/test/layer_tree_pixel_test.cc

Index: cc/test/layer_tree_pixel_test.cc
diff --git a/cc/test/layer_tree_pixel_test.cc b/cc/test/layer_tree_pixel_test.cc
index c5d2125c120365733859d31ec02e26f83fd0bbee..2792f660a5ccd8454e623ff23763b0f500bbf08d 100644
--- a/cc/test/layer_tree_pixel_test.cc
+++ b/cc/test/layer_tree_pixel_test.cc
@@ -21,7 +21,6 @@
 #include "cc/trees/layer_tree_impl.h"
 #include "gpu/command_buffer/client/gl_in_process_context.h"
 #include "gpu/command_buffer/client/gles2_implementation.h"
-#include "ui/gl/gl_implementation.h"
 
 using gpu::gles2::GLES2Interface;
 
@@ -55,8 +54,6 @@ scoped_ptr<OutputSurface> LayerTreePixelTest::CreateOutputSurface(
 
     case GL_WITH_DEFAULT:
     case GL_WITH_BITMAP: {
-      CHECK(gfx::InitializeStaticGLBindings(gfx::kGLImplementationOSMesaGL));
-
       output_surface = make_scoped_ptr(
           new PixelTestOutputSurface(new TestInProcessContextProvider));
       break;
@@ -316,8 +313,6 @@ void LayerTreePixelTest::CopyBitmapToTextureMailboxAsTexture(
   DCHECK_GT(bitmap.width(), 0);
   DCHECK_GT(bitmap.height(), 0);
 
-  CHECK(gfx::InitializeStaticGLBindings(gfx::kGLImplementationOSMesaGL));
-
   scoped_ptr<gpu::GLInProcessContext> context = CreateTestInProcessContext();
   GLES2Interface* gl = context->GetImplementation();