GDB support for Android in devtools' debugger.

README.md

 Mojo
 ====
 
 Mojo is an effort to extract a common platform out of Chrome's renderer and
 plugin processes that can support multiple types of sandboxed content, such as
 HTML, Pepper, or NaCl.
 
 ## Set-up and code check-out
 
 The instructions below only need to be done once. Note that a simple "git clone"
@@ skipping 247 matching lines @@
 
 #### Android crash stacks
 When Mojo shell crashes on Android ("Unfortunately, Mojo shell has stopped.")
 due to a crash in native code, `debugger` can be used to find and symbolize the
 stack trace present in the device log:
 
 ```
 mojo/devtools/common/debugger device stack
 ```
 
+#### GDB support

[ppi, 2015/07/09 13:12:38]

"support" is redundant, let's just say "gdb" or "Attaching gdb"?

[etiennej, 2015/07/15 07:13:20]

Done.

+It is possible to inspect a Mojo Shell process using GDB. The `debugger` script
+can be used to launch GDB and attach it to a running shell process (android
+only):
+```
+mojo/devtools/common/debugger gdb attach

[ppi, 2015/07/09 13:12:38]

I just tried to do just that, and the process hanged:

$ mojo/devtools/common/debugger gdb attach


^CTraceback (most recent call last):
  File "mojo/devtools/common/debugger", line 259, in <module>
    sys.exit(main())
  File "mojo/devtools/common/debugger", line 256, in main
    return args.func(args)
  File "mojo/devtools/common/debugger", line 162, in _gdb_attach
    _GetDirAbove('depot_tools'), 'depot_tools', 'third_party', 'gsutil',
  File "mojo/devtools/common/debugger", line 26, in _GetDirAbove
    if dirname in os.listdir(path):
KeyboardInterrupt


There are two action items here:

 - could you make it work out of the box in the regular mojo checkout?
 - we probably want to have an explicit error message instead of infinite loop
if some directory / tool cannot be located

[etiennej, 2015/07/15 07:13:20]

I don't know how your "regular mojo checkout" differs from mine, it might be
worth investigating. In any case, we now have an explicit error message and no
more infinite loop.

+```
+
 ### Android set-up
 
 #### Adb
 
 For the Android tooling to work, you will need to have `adb` in your PATH. For
 that, you can either run:
 ```
 source build/android/envsetup.sh
 ```
 
@@ skipping 20 matching lines @@
 ```
 adb logcat | ./tools/android_stack_parser/stack
 ```
 
 ### Running manually on Linux
 
 If you wish to, you can also run the Linux Mojo shell directly with no wrappers:
 ```
 ./out/Debug/mojo_shell mojo:spinning_cube
 ```