Don't use a global share group for the passthrough command buffer contexts.

gpu/command_buffer/common/gles2_cmd_utils.h

Index: gpu/command_buffer/common/gles2_cmd_utils.h
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.h b/gpu/command_buffer/common/gles2_cmd_utils.h
index 969a7245060578b393d50448dbb026afce99cd0c..2d378a93e438be26ffacc1cef5986154612475f7 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.h
+++ b/gpu/command_buffer/common/gles2_cmd_utils.h
@@ -308,6 +308,8 @@ enum ContextType {
   CONTEXT_TYPE_LAST = CONTEXT_TYPE_OPENGLES3
 };
 GLES2_UTILS_EXPORT bool IsWebGLContextType(ContextType context_type);
+GLES2_UTILS_EXPORT bool IsWebGL1OrES2ContextType(ContextType context_type);
+GLES2_UTILS_EXPORT bool IsWebGL2OrES3ContextType(ContextType context_type);
 
 struct GLES2_UTILS_EXPORT ContextCreationAttribHelper {
   ContextCreationAttribHelper();