telemetry: Fix killing the perf profiler

build/android/pylib/device/device_utils.py

Index: build/android/pylib/device/device_utils.py
diff --git a/build/android/pylib/device/device_utils.py b/build/android/pylib/device/device_utils.py
index f201ef36b8bf04fa20881109d11c6225f8322bfb..a06491e7f6dd59fff4d4679261368eb04cb50701 100644
--- a/build/android/pylib/device/device_utils.py
+++ b/build/android/pylib/device/device_utils.py
@@ -736,7 +736,7 @@ class DeviceUtils(object):
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    pids = self.GetPids(process_name)
+    pids = [pid for (_, pid) in self._GetProcessPidPairs(process_name)]
     if not pids:
       if quiet:
         return 0
@@ -744,13 +744,13 @@ class DeviceUtils(object):
         raise device_errors.CommandFailedError(
             'No process "%s"' % process_name, str(self))
 
-    cmd = ['kill', '-%d' % signum] + pids.values()
+    cmd = ['kill', '-%d' % signum] + pids
     self.RunShellCommand(cmd, as_root=as_root, check_return=True)
 
     if blocking:
       # TODO(perezu): use timeout_retry.WaitFor
       wait_period = 0.1
-      while self.GetPids(process_name):
+      while self._GetProcessPidPairs(process_name):
         time.sleep(wait_period)
 
     return len(pids)
@@ -1564,26 +1564,23 @@ class DeviceUtils(object):
     """
     return self.GetProp('ro.product.cpu.abi')
 
-  @decorators.WithTimeoutAndRetriesFromInstance()
-  def GetPids(self, process_name, timeout=None, retries=None):
-    """Returns the PIDs of processes with the given name.
+  def _GetProcessPidPairs(self, process_name):

[jbudorick, 2015/07/24 17:10:56]

I think I'd prefer making a breaking change to the GetPids interface by having
it return

{
  'process': [process_pid0, process_pid1, ...]
}

instead of adding a separate function. I imagine most clients of GetPids would
want to know all of the pids that a given process is using, not just an
arbitrary one.

+    """Returns a list of (process, pid) pairs for all matching processes.
 
     Note that the |process_name| is often the package name.
 
     Args:
       process_name: A string containing the process name to get the PIDs for.
-      timeout: timeout in seconds
-      retries: number of retries
 
     Returns:
-      A dict mapping process name to PID for each process that contained the
+      A list with (process, pid) pairs for all processes that contained the
       provided |process_name|.
 
     Raises:
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    procs_pids = {}
+    procs_pids = []
     try:
       ps_output = self._RunPipedShellCommand(
           'ps | grep -F %s' % cmd_helper.SingleQuote(process_name))
@@ -1599,12 +1596,37 @@ class DeviceUtils(object):
       try:
         ps_data = line.split()
         if process_name in ps_data[-1]:
-          procs_pids[ps_data[-1]] = ps_data[1]
+          pid, process = ps_data[1], ps_data[-1]
+          procs_pids.append((process, pid))
       except IndexError:
         pass
     return procs_pids
 
   @decorators.WithTimeoutAndRetriesFromInstance()
+  def GetPids(self, process_name, timeout=None, retries=None):
+    """Returns the PIDs of processes with the given name.
+
+    Note that the |process_name| is often the package name.
+
+    If there are multiple instances of the same process, only one of the PIDs
+    will be returned.
+
+    Args:
+      process_name: A string containing the process name to get the PIDs for.
+      timeout: timeout in seconds
+      retries: number of retries
+
+    Returns:
+      A dict mapping process name to PID for each process that contained the
+      provided |process_name|.
+
+    Raises:
+      CommandTimeoutError on timeout.
+      DeviceUnreachableError on missing device.
+    """
+    return dict(self._GetProcessPidPairs(process_name))
+
+  @decorators.WithTimeoutAndRetriesFromInstance()
   def TakeScreenshot(self, host_path=None, timeout=None, retries=None):
     """Takes a screenshot of the device.