validate CHROME_SRC setting to avoid confusion

build/android/envsetup.sh

Index: build/android/envsetup.sh
diff --git a/build/android/envsetup.sh b/build/android/envsetup.sh
index 6ed168de6aa7e5d306736d3d884406a822f445e4..63c6f869efef76bf660d66276d1fac110e3a4c4f 100755
--- a/build/android/envsetup.sh
+++ b/build/android/envsetup.sh
@@ -93,7 +93,15 @@ export PATH=$PATH:${ANDROID_TOOLCHAIN}
 
 if [ -z "${CHROME_SRC}" ]; then
   # If $CHROME_SRC was not set, assume current directory is CHROME_SRC.
-  export CHROME_SRC=$(readlink -f .)
+  export CHROME_SRC="${PWD}"
+fi
+
+if [ "${PWD/"${CHROME_SRC}"/}" == "${PWD}" ]; then

[John Grabowski, 2012/05/25 16:27:19]

Sorry I didn't mention this the first time, but...
I'm not sure I understand this syntax?
What is "${PWD/"${CHROME_SRC}"/}" supposed to do?
I think it'll equal "" always since this would resolve to ${PWD//homedir/src/},
and you can't have a / in a variable name.

[Wei James(wistoch), 2012/05/26 05:01:47]

if we are in the correct directory and CHROME_SRC is set correctly, it will
equal to "". but if not, it will not. 

for example, on my box: 

$echo $CHROME_SRC
/home/wistoch/workspace/chromium-android/src
$echo $PWD
/home/wistoch/workspace/chromium-android/src
$echo ${PWD/$CHROME_SRC/}
it is equal to "". 

in case it is not correct: 
$export CHROME_SRC=/home/wistoch/workspace/chromium-android-x86/src
$ echo ${PWD/$CHROME_SRC/}
/home/wistoch/workspace/chromium-android/src

so ${PWD/$CHROME_SRC/} equal to ${PWD}, so we know something is wrong. 

[John Grabowski, 2012/05/29 17:50:23]

OK... it's a little cryptic.
Can you add this comment in the code?

[Wei James(wistoch), 2012/05/30 03:00:15]

fixed. thanks

+  # If current directory is not in $CHROME_SRC, it might be set for other
+  # source tree.
+  echo "Warning: Current directory is out of CHROME_SRC, it may not be \
+the one you want."
+  echo "${CHROME_SRC}"
 fi
 
 if [ ! -d "${CHROME_SRC}" ]; then