Add optional logging prefix to info, warn and error messages.

common.sh

Index: common.sh
diff --git a/common.sh b/common.sh
index 1d25074316d2a336046e3a5311cc1d6de5b02a37..a26c29b4d26903db7e70bced398cac18c0199e0b 100644
--- a/common.sh
+++ b/common.sh
@@ -383,15 +383,15 @@ V_BOLD_RED="\e[1;31m"
 V_BOLD_YELLOW="\e[1;33m"
 
 function info {
-  echo -e >&2 "${V_BOLD_GREEN}INFO   : $1${V_VIDOFF}"
+  echo -e >&2  "${V_BOLD_GREEN}INFO    ${CROS_LOG_PREFIX:-""}: $1${V_VIDOFF}"
 }
 
 function warn {
-  echo -e >&2 "${V_BOLD_YELLOW}WARNING: $1${V_VIDOFF}"
+  echo -e >&2 "${V_BOLD_YELLOW}WARNING ${CROS_LOG_PREFIX:-""}: $1${V_VIDOFF}"
 }
 
 function error {
-  echo -e >&2   "${V_BOLD_RED}ERROR  : $1${V_VIDOFF}"
+  echo -e >&2    "${V_BOLD_RED}ERROR   ${CROS_LOG_PREFIX:-""}: $1${V_VIDOFF}"
 }
 
 function die {