android: Add systrace and combined trace support to adb_profile_chrome

android: Add systrace and combined trace support to adb_profile_chrome

This patch adds systrace support to adb_profile_chrome. You can either
either capture a standalone systrace or a combined Chrome + systrace
which includes data from both sources.

The advantages of a combined trace compared to a normal systrace with
the 'webview' category are:

 - Support for advanced Chrome trace features such as object dumps
   (e.g., --trace-cc and --trace-gpu), instant events ('X') and flow
   events.
 - Reduced tracing overhead since Chrome trace events do not need to
   make the trip through the kernel trace marker file.

Note that viewing combined traces requires some further work in Trace
Viewer to properly align the clocks from different event streams.

This patch also removes the standalone --start, --stop and --download
options from the script because they are of dubious value and supporting
them with systrace is not straightforward.

BUG=294883
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=228669

[bulach, 2013-10-04 14:30:11]

lgtm, just one question about the "continuous" below.. thanks!

https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
File build/android/adb_profile_chrome.py (right):

https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
build/android/adb_profile_chrome.py:55: # that the trace file is ready to be
downloaded.
nit: how about s/Download/Pull/g ?
I think we normally have "Pull" when talking about device -> host instead of
download, wdyt?

https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
build/android/adb_profile_chrome.py:121: return subprocess.check_output(cmd)
comment from tonyg :)
there's a pylib/cmd_helper.py, or even better, just use
AndroidCommands::RunShellCommand, no need to messup with device serial or
anything..

https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
build/android/adb_profile_chrome.py:304: if not options.time:
how does this play with --continuous? should we remove that option as well?

[Sami, 2013-10-04 14:38:24]

On 2013/10/04 14:30:11, bulach wrote:
> there's a pylib/cmd_helper.py, or even better, just use
> AndroidCommands::RunShellCommand, no need to messup with device serial or
> anything..

RunShellCommand doesn't look thread safe, but I'll take a look at cmd_helper.
Thanks!

[Sami, 2013-10-10 18:11:36]

Hi Tony, I've moved the meat of https://codereview.chromium.org/25883003/ here
like you and Marcus suggestes and have added a continuous mode that telemetry
could use when calling this script. PTAL.

[Sami, 2013-10-15 09:29:24]

On 2013/10/04 14:30:11, bulach wrote:
> lgtm, just one question about the "continuous" below.. thanks!
> 
>
https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
> File build/android/adb_profile_chrome.py (right):
> 
>
https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
> build/android/adb_profile_chrome.py:55: # that the trace file is ready to be
> downloaded.
> nit: how about s/Download/Pull/g ?
> I think we normally have "Pull" when talking about device -> host instead of
> download, wdyt?

Done.
 
>
https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
> build/android/adb_profile_chrome.py:121: return subprocess.check_output(cmd)
> comment from tonyg :)
> there's a pylib/cmd_helper.py, or even better, just use
> AndroidCommands::RunShellCommand, no need to messup with device serial or
> anything..

Thanks for the hint; I'm using cmd_helper now.
 
>
https://codereview.chromium.org/25686006/diff/8001/build/android/adb_profile_...
> build/android/adb_profile_chrome.py:304: if not options.time:
> how does this play with --continuous? should we remove that option as well?

Since we now want to use this script from telemetry as well, I've split
--continuous to two different options: --continuous for tracing until the user
hits enter and --ring-buffer to support really long time intervals by only
saving the final contents of the trace buffer. The two can also be used in
combination.

[commit-bot: I haz the power, 2013-10-15 09:31:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/skyostil@chromium.org/25686006/16001

[commit-bot: I haz the power, 2013-10-15 12:10:52]

Change committed as 228669