Added EGL based GLContext.

Python script to generate code to dynamically bind to GL functions (native GL, OSMesa, EGL or mock GL for unit tests). This replaces GLEW because GLEW doesn't bind to the GLES dialect of GL.
Moved the mock GL code into app/gfx/gl.
Updated the GPU code and AcceleratedSurface to use the new GL bindings.


TEST=trybots
BUG=none

Review URL: http://codereview.chromium.org/2134006

git-svn-id: http://src.chromium.org/svn/trunk/src/build@49332 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -255,9 +255,6 @@
 
     # Enable new NPDevice API.
     'enable_new_npdevice_api%': 0,
-    
-    # Enable OpenGL ES.
-    'enable_gles%': 0,
 
     # Enable EGLImage support in OpenMAX
     'enable_eglimage%': 0,
@@ -443,11 +440,6 @@
           'ENABLE_GPU=1',
         ],
       }],
-      ['enable_gles==1', {
-        'defines': [
-          'ENABLE_GLES=1',
-        ],
-      }],
       ['enable_eglimage==1', {
         'defines': [
           'ENABLE_EGLIMAGE=1',