[Telemetry] Add the ability to flush the system file cache to platform.

tools/telemetry/telemetry/core/util.py

Index: tools/telemetry/telemetry/core/util.py
diff --git a/tools/telemetry/telemetry/core/util.py b/tools/telemetry/telemetry/core/util.py
index 2fe792feccc02b74fc9e685053f7cf7d0d366dfa..5b11640fe38ad9fb1f443f914fe5075902ee7d2c 100644
--- a/tools/telemetry/telemetry/core/util.py
+++ b/tools/telemetry/telemetry/core/util.py
@@ -85,3 +85,16 @@ def CloseConnections(tab):
                              chrome.benchmarking.closeConnections()""")
   except Exception:
     pass
+
+def GetBuildDirectories():
+  """Yields all combination of Chromium build output directories."""
+  build_dirs = ['build',
+                'out',
+                'sconsbuild',
+                'xcodebuild']
+
+  build_types = ['Debug', 'Debug_x64', 'Release', 'Release_x64']
+
+  for build_dir in build_dirs:
+    for build_type in build_types:
+      yield build_dir, build_type