Make Timur's recent drmemory script changes work on Cygwin.

tools/valgrind/chrome_tests.sh

 #!/bin/bash
 
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Set up some paths and re-direct the arguments to chrome_tests.py
 
 export THISDIR=`dirname $0`
 ARGV_COPY="$@"
@@ skipping 44 matching lines @@
 
   PATH="${CHROME_VALGRIND}/bin:$PATH"
   # We need to set these variables to override default lib paths hard-coded into
   # Valgrind binary.
   export VALGRIND_LIB="$CHROME_VALGRIND/lib/valgrind"
   export VALGRIND_LIB_INNER="$CHROME_VALGRIND/lib/valgrind"
 fi
 
 if [ "$NEEDS_DRMEMORY" == "1" ]
 then
-  export DRMEMORY_PATH=$THISDIR/../../third_party/drmemory
-  export DRMEMORY_SFX=$DRMEMORY_PATH/drmemory-windows-sfx.exe
-  if [ ! -f "$DRMEMORY_SFX" ]
+  if [ -z "$DRMEMORY_COMMAND" ]
   then
-    echo "Can't find Dr. Memory executables."
-    echo "See http://www.chromium.org/developers/how-tos/using-valgrind/dr-memory"
-    echo "for the instructions on how to get them."
-    exit 1
+    DRMEMORY_PATH="$THISDIR/../../third_party/drmemory"
+    DRMEMORY_SFX="$DRMEMORY_PATH/drmemory-windows-sfx.exe"
+    if [ ! -f "$DRMEMORY_SFX" ]
+    then
+      echo "Can't find Dr. Memory executables."
+      echo "See http://www.chromium.org/developers/how-tos/using-valgrind/dr-memory"
+      echo "for the instructions on how to get them."
+      exit 1
+    fi
+
+    chmod +x "$DRMEMORY_SFX"  # Cygwin won't run it without +x.
+    "$DRMEMORY_SFX" -o"$DRMEMORY_PATH/unpacked" -y
+    export DRMEMORY_COMMAND="$DRMEMORY_PATH/unpacked/bin/drmemory.exe"
   fi
-
-  chmod +x "$DRMEMORY_SFX"  # Cygwin won't run it without +x.
-  "$DRMEMORY_SFX" -o"$DRMEMORY_PATH/unpacked" -y
-  export DRMEMORY_COMMAND=$DRMEMORY_PATH/unpacked/bin/drmemory.exe
 fi
 
 PYTHONPATH=$THISDIR/../python/google python \
            "$THISDIR/chrome_tests.py" $ARGV_COPY