allow dumping the nav cache from the browser

Adding this about:debug flavor allows dumping the
nav cache from a script over usb without user
interaction. The script for me looks like:

function pullnav()
{
   adb shell am start about:debug.nav
   sleep 1
   adb pull data/data/com.android.browser/navlog /android/$1.cpp
   adb shell rm data/data/com.android.browser/navlog
   kate -u /android/$1.cpp &
}

which pulls up the nav dump into a local editor.

bug:3364574
Change-Id: Ie6b3491b4b9e4490d8229402f4f3770879eff36d
1 file changed