Android Debugging Instructions

Chrome on Android has java and c/c++ code. Each “side” have its own set of tools for debugging. Here's some tips.

Launching the app

You can launch the app by using one of the wrappers.

out/Default/bin/content_shell_apk launch [--args='--foo --bar'] 'data:text/html;utf-8,<html>Hello World!</html>'
out/Default/bin/chrome_public_apk launch [--args='--foo --bar'] 'data:text/html;utf-8,<html>Hello World!</html>'

Log output

Chromium logging from LOG(INFO) etc., is directed to the Android logcat logging facility. You can filter the messages, e.g. view chromium verbose logging, everything else at warning level with:

adb logcat chromium:V cr.SomeComponent:V *:W
# or:
out/Default/bin/chrome_public_apk logcat

Warnings for Blink developers

  • Do not use fprintf or printf debugging! This does not redirect to logcat.

  • Redirecting stdio to logcat, as documented here, has a bad side-effect that it breaks See here for details.

Take a screenshot

While your phone is plugged into USB, use the tool in build/android. should have put it in your path.

build/android/ /tmp/screenshot.png

Inspecting the view hierarchy

You can use either hierarchy viewer or monitor to see the Android view hierarchy and see the layout and drawing properties associated with it.

While your phone is plugged into USB, you can inspect the Android view hierarchy using the following command:


Setting ANDROID_HVPROTO allows you to inspect debuggable apps on non-rooted devices. When building a local version of Chromium, the build tools automatically add android:debuggable=true to the AndroidManifest.xml, which will allow you to inspect them on rooted devices.

Want to add some additional information to your Views? You can do that by adding the @ViewDebug.ExportedProperty annotation.


private int mSuperNiftyDrawingProperty;

Debugging Java

For both apk and test targets, pass --wait-for-java-debugger to the wrapper scripts.


# Install, launch, and wait:
out/Default/bin/chrome_public_apk run --wait-for-java-debugger

# Launch, and have GPU process wait rather than Browser process:
out/Default/bin/chrome_public_apk launch --wait-for-java-debugger --debug-process-name privileged_process0

# Have Renderers wait:
out/Default/bin/chrome_public_apk launch --args="--renderer-wait-for-java-debugger"

# Have tests wait:
out/Default/bin/run_chrome_public_test_apk --wait-for-java-debugger
out/Default/bin/run_chrome_junit_tests --wait-for-java-debugger  # Specify custom port via --debug-socket=9999

Android Studio

  • Open Android Studio (instructions)
  • Click “Run”->“Attach debugger to Android process” (see here for more). Click “Run”->“Attach to Local Process...” for Robolectric junit tests.


  • In Eclipse, make a debug configuration of type “Remote Java Application”. Choose a “Name” and set “Port” to 8700.

  • Make sure Eclipse Preferences > Run/Debug > Launching > “Build (if required) before launching” is unchecked.

  • Run Android Device Monitor:

  • Now select the process you want to debug in Device Monitor (the port column should now mention 8700 or xxxx/8700).

  • Run your debug configuration, and switch to the Debug perspective.

Debugging C/C++

Use the wrapper script gdb command to enter into a gdb shell.

# Attaches to browser process.
out/Default/bin/content_shell_apk gdb
out/Default/bin/chrome_public_apk gdb

# Attaches to gpu process.
out/Default/bin/chrome_public_apk gdb --debug-process-name privileged_process0

# Attach to other processes ("chrome_public_apk ps" to show pids).
out/Default/bin/chrome_public_apk gdb --pid $PID

Waiting for Debugger on Early Startup

Set the target command line flag with --wait-for-debugger.

Launch the debugger using one of the scripts from above.

Type info threads and look for a line like:

11 Thread 2564  clock_gettime () at bionic/libc/arch-arm/syscalls/clock_gettime.S:11

or perhaps:

1  Thread 10870      0x40127050 in nanosleep () from /tmp/user-adb-gdb-libs/system/lib/

We need to jump out of its sleep routine:

(gdb) thread 11
(gdb) up
(gdb) up
(gdb) return
Make base::debug::BreakDebugger() return now? (y or n) y
(gdb) continue

Symbolizing Crash Stacks and Tombstones (C++)

If a crash has generated a tombstone in your device, use:

build/android/ --output-directory out/Default

If you have a stack trace (from adb logcat) that needs to be symbolized, copy it into a text file and symbolize with the following command (run from ${CHROME_SRC}):

third_party/android_platform/development/scripts/stack --output-directory out/Default [tombstone file | dump file]

stack can also take its input from stdin:

adb logcat -d | third_party/android_platform/development/scripts/stack --output-directory out/Default


third_party/android_platform/development/scripts/stack --output-directory out/Default ~/crashlogs/tombstone_07-build231.txt

Deobfuscating Stack Traces (Java)

You will need the ProGuard mapping file that was generated when the application that crashed was built. When building locally, these are found in:


Build the java_deobfuscate tool:

ninja -C out/Default java_deobfuscate

Then run it via:

# For a file:
out/Default/bin/java_deobfuscate PROGUARD_MAPPING_FILE.mapping < FILE
# For logcat:
adb logcat | out/Default/bin/java_deobfuscate PROGUARD_MAPPING_FILE.mapping

Get WebKit code to output to the adb log

In your build environment:

adb root
adb shell stop
adb shell setprop log.redirect-stdio true
adb shell start

In the source itself, use fprintf(stderr, "message"); whenever you need to output a message.

Debug unit tests with GDB

To run unit tests use the following command:

out/Debug/bin/run_test_name -f <test_filter_if_any> --wait-for-debugger -t 6000

That command will cause the test process to wait until a debugger is attached.

To attach a debugger:

build/android/adb_gdb --output-directory=out/Default --package-name=org.chromium.native_test

After attaching gdb to the process you can use it normally. For example:

(gdb) break main
Breakpoint 1 at 0x9750793c: main. (2 locations)
(gdb) continue