Enable GLX/EGL backend switching while run HW video decode with libva.

content/content_common.gypi

Index: content/content_common.gypi
diff --git a/content/content_common.gypi b/content/content_common.gypi
index ef8293d578f05935728354f5fdf28307706c9daf..a12aeda97f05032353128b5ddc616765e681ca85 100644
--- a/content/content_common.gypi
+++ b/content/content_common.gypi
@@ -517,7 +517,14 @@
         ],
       },
     }],
-    ['target_arch != "arm" and chromeos == 1 and use_x11 == 1', {
+    ['target_arch != "arm" and OS!="win" and OS!="andorid" and OS!="ios" and use_x11 == 1', {
+      'variables': {
+        'use_video_glx%': 1,
+      },
+      'use_video_glx%': '<(use_video_glx)',
+      'dependencies': [
+        '../media/media.gyp:media',
+      ],
       'sources': [
         'common/gpu/media/h264_dpb.cc',
         'common/gpu/media/h264_dpb.h',
@@ -532,6 +539,27 @@
       'include_dirs': [
         '<(DEPTH)/third_party/libva',
       ],
+      'conditions': [
+        ['use_video_glx == 1 or chromeos == 1', {
+          'defines': [
+            'VIDEO_TEXTURE_GLX_BACKEND',
+          ],
+        }],
+        ['use_video_glx == 0 and chromeos == 0', {
+          'defines': [
+            'VIDEO_TEXTURE_EGL_BACKEND',
+          ],
+          'include_dirs': [
+            '<(DEPTH)/third_party/khronos',
+          ],
+          'link_settings': {
+            'libraries': [
+              '-lEGL',
+              '-lGLESv2',
+            ],
+          },
+        }],
+      ],
     }],
     ['OS=="win"', {
       'dependencies': [