telemetry: Pass correct objdump binary to perf

Use the --objdump argument to point perf to the correct ARM objdump
binary so that it can properly annotate source code. Since this requires
a fairly new version of perf (3.10), don't add the argument to the
default set of perf options but rather just print a hint.

See http://www.chromium.org/developers/telemetry/profiling for
instructions on how to get a newer version of perf.

NOTRY=true

Review URL: https://codereview.chromium.org/137783020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245241 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py

@@ -77,6 +77,12 @@ Try rerunning this script under sudo or setting
     if self._is_android:
       print 'On Android, assuming $CHROMIUM_OUT_DIR/Release/lib has a fresh'
       print 'symbolized library matching the one on device.'
+      objdump_path = os.path.join(os.environ.get('ANDROID_TOOLCHAIN',
+                                                 '$ANDROID_TOOLCHAIN'),
+                                  'arm-linux-androideabi-objdump')
+      print 'If you have recent version of perf (3.10+), append the following '
+      print 'to see annotated source code (by pressing the \'a\' key): '
+      print '  --objdump %s' % objdump_path
       cmd += ' ' + ' '.join(self._PrepareAndroidSymfs())
     print 'To view the profile, run:'
     print ' ', cmd