add ENABLE_GLES flag for conditional complilation of GLES

build/common.gypi

Index: build/common.gypi
===================================================================
--- build/common.gypi	(revision 44997)
+++ build/common.gypi	(working copy)
@@ -321,6 +321,15 @@
       }, {  # GPU plugin not supported
         'enable_gpu%': 0,
       }],
+      # Compute based on OS, target architecture and device whether GLES
+      # is supported
+      [ 'OS=="linux" and target_arch=="arm" and chromeos==1', {
+        # Enable a variable used elsewhere throughout the GYP files to determine
+        # whether to compile in the sources for the GLES support.
+        'enable_gles%': 1,
+      }, {  # GLES not supported
+        'enable_gles%': 0,
+      }],
     ],
 
     # NOTE: When these end up in the Mac bundle, we need to replace '-' for '_'
@@ -405,6 +414,11 @@
           'ENABLE_GPU=1',
         ],
       }],
+      ['enable_gles==1', {
+        'defines': [
+          'ENABLE_GLES=1',
+        ],
+      }],
       ['coverage!=0', {
         'conditions': [
           ['OS=="mac"', {