Add profiling_controller that manages profilers.

tools/telemetry/telemetry/core/platform/profiling_controller_backend.py

Index: tools/telemetry/telemetry/core/platform/profiling_controller_backend.py
diff --git a/tools/telemetry/telemetry/core/platform/profiling_controller_backend.py b/tools/telemetry/telemetry/core/platform/profiling_controller_backend.py
new file mode 100644
index 0000000000000000000000000000000000000000..1775fc015f12d540c3dd54a09853e1abfaeed0c0
--- /dev/null
+++ b/tools/telemetry/telemetry/core/platform/profiling_controller_backend.py
@@ -0,0 +1,53 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+from telemetry.core.platform.profiler import profiler_finder
+
+
+class ProfilingControllerBackend(object):
+  def __init__(self, platform_backend):
+    self._platform_backend = platform_backend
+    self._active_profilers = []
+    self._profilers_states = {}
+
+  def Start(self, profiler_name, base_output_file):
+    """Starts profiling using |profiler_name|. Results are saved to
+    |base_output_file|.<process_name>."""
+    assert not self._active_profilers, 'Already profiling. Must stop first.'
+
+    browser_backend = None
+    # Note that many profilers doesn't rely on browser_backends, so the number
+    # of running_browser_backends may not matter for them.
+    if len(self._platform_backend.running_browser_backends) == 1:
+      browser_backend = self._platform_backend.running_browser_backends[0]
+    else:
+      raise NotImplementedError()
+
+    profiler_class = profiler_finder.FindProfiler(profiler_name)
+
+    if not profiler_class.is_supported(browser_backend.browser_type):
+      raise Exception('The %s profiler is not '
+                      'supported on this platform.' % profiler_name)
+
+    if not profiler_class in self._profilers_states:
+      self._profilers_states[profiler_class] = {}
+
+    self._active_profilers.append(
+        profiler_class(browser_backend, self._platform_backend,
+            base_output_file, self._profilers_states[profiler_class]))
+
+  def Stop(self):
+    """Stops all active profilers and saves their results.
+
+    Returns:
+      A list of filenames produced by the profiler.
+    """
+    output_files = []
+    for profiler in self._active_profilers:
+      output_files.extend(profiler.CollectProfile())
+    self._active_profilers = []
+    return output_files
+
+  def WillCloseBrowser(self, browser_backend):
+    for profiler_class in self._profilers_states:
+      profiler_class.WillCloseBrowser(browser_backend, self._platform_backend)