Added a stub driver implementation for Mesa EGL.

ppapi/ppapi.gyp

Index: ppapi/ppapi.gyp
===================================================================
--- ppapi/ppapi.gyp	(revision 69161)
+++ ppapi/ppapi.gyp	(working copy)
@@ -3,6 +3,9 @@
 # found in the LICENSE file.
 
 {
+  'includes': [
+    '../third_party/mesa/mesa.gypi',
+  ],
   'variables': {
     'chromium_code': 1,  # Use higher warning level.
   },
@@ -255,6 +258,43 @@
       ],
     },
     {
+      'target_name': 'ppapi_egl',
+      'type': 'static_library',
+      'dependencies': [
+        'ppapi_c',
+      ],
+      'include_dirs': [
+        'lib/gl/include',
+      ],
+      'defines': [
+        # Do not export internal Mesa funcations. Exporting them is not
+        # required becuase we are compiling both - API dispatcher and driver
+        # into a single library.
+        'PUBLIC=',
+        # Define a new PPAPI platform.
+        '_EGL_PLATFORM_PPAPI=_EGL_NUM_PLATFORMS',
+        '_EGL_NATIVE_PLATFORM=_EGL_PLATFORM_PPAPI',
+      ],
+      'conditions': [
+        ['OS=="win"', {
+          'defines': [
+            '_EGL_OS_WINDOWS',
+          ],
+        }],
+        ['OS=="mac"', {
+          # TODO(alokp): Make this compile on mac.
+          'suppress_wildcard': 1,
+        }],
+      ],
+      'sources': [
+        # Mesa EGL API dispatcher sources.
+        '<@(mesa_egl_sources)',
+        # PPAPI EGL driver sources.
+        'lib/gl/egl/egldriver.c',
+        'lib/gl/egl/egldriver_ppapi.c',
+      ],
+    },
+    {
       'target_name': 'ppapi_example',
       'dependencies': [
         'ppapi_cpp'