getsdcardpath, getscreenshotpath, getlastscreenshot

Added a few new functions to envsetup.sh:
- getsdcardpath() returns the sdcard path. This will be more useful
  when multiuser storage complicates the sdcard path.
- getscreenshotpath() returns the path to screenshots
- getlastscreenshot() adb pulls the most recently-taken screenshot

Change-Id: I851145088344dff6f1672f0a423201f3aa3e4390

envsetup.sh

@@ -979,6 +979,28 @@ function getbugreports()
     done
 }
 
+function getsdcardpath()
+{
+    adb ${adbOptions} shell echo -n \$\{EXTERNAL_STORAGE\}
+}
+
+function getscreenshotpath()
+{
+    echo "$(getsdcardpath)/Pictures/Screenshots"
+}
+
+function getlastscreenshot()
+{
+    local screenshot_path=$(getscreenshotpath)
+    local screenshot=`adb ${adbOptions} ls ${screenshot_path} | grep Screenshot_[0-9-]*.*\.png | sort -rk 3 | cut -d " " -f 4 | head -n 1`
+    if [ "$screenshot" = "" ]; then
+        echo "No screenshots found."
+        return
+    fi
+    echo "${screenshot}"
+    adb ${adbOptions} pull ${screenshot_path}/${screenshot}
+}
+
 function startviewserver()
 {
     local port=4939