Add a test for checking objects reported by DevTools memory instrumentation not allocated by tcmall…

chrome/test/pyautolib/remote_inspector_client.py

Index: chrome/test/pyautolib/remote_inspector_client.py
diff --git a/chrome/test/pyautolib/remote_inspector_client.py b/chrome/test/pyautolib/remote_inspector_client.py
index bda06c7ebef254b27e3e005115144c35ccc99e88..56575b49dde397e027d17e1643464a511cae3ece 100755
--- a/chrome/test/pyautolib/remote_inspector_client.py
+++ b/chrome/test/pyautolib/remote_inspector_client.py
@@ -711,6 +711,11 @@ class NativeMemorySnapshot(object):
   Public Methods:
     GetProcessPrivateMemorySize: The process total size.
     GetUnknownSize: Size of not instrumented parts.
+    GetInstrumentedObjectsCount: Number of instrumented objects traversed by
+        DevTools memory instrumentation.
+    GetNumberOfInstrumentedObjectsNotInHeap: Number of instrumented objects
+        visited by DevTools memory instrumentation that haven't been allocated
+        by tcmalloc.
     FindMemoryBlock: Given an array of memory block names return the block.
   """
   def __init__(self, root_block):
@@ -726,6 +731,30 @@ class NativeMemorySnapshot(object):
       known_size += child['size']
     return self.GetProcessPrivateMemorySize() - known_size
 
+  def GetInstrumentedObjectsCount(self):
+    """Returns number of objects visited by DevTools memory instrumentation.
+
+    Returns:
+      None if the number is not available.

[dennis_jeffrey, 2012/10/04 22:02:57]

nit: I'd prefer the "Returns:" section to fully describe what is returned by
this function, rather than only stating what is returned in the exceptional
case.  But that would basically cause you to have to repeat what's in the
one-line header of this docstring, which adds redundancy.  So while it seems
weird to me that the "Returns:" section itself only tells part of the story, I
think it's probably ok here.

[yurys, 2012/10/05 07:34:53]

Done. Changed the text to "Number of known instrumented objects or None if it is
not available."

Personally I don't like the fact that the information is repeated 4 times: 1) in
the method's name; 2) in the list of public methods; 3) in the method's 1-line
description; 4) in the return value description. The method itself is trivial
and it would be easier to skim through its code to learn details that are not
obvious from its name(like what it returns if the number is not available) than
reading all the commentaries.

+    """
+    memory_block = self.FindMemoryBlock(['ProcessPrivateMemory',
+        'InstrumentedObjectsCount'])
+    if not memory_block is None:
+      return memory_block['size']
+    return None
+
+  def GetNumberOfInstrumentedObjectsNotInHeap(self):
+    """Returns number of instrumented objects unknown to tcmalloc.
+
+    Returns:
+      None if the number is not available.
+    """
+    memory_block = self.FindMemoryBlock(['ProcessPrivateMemory',
+        'InstrumentedButNotAllocatedObjectsCount'])
+    if not memory_block is None:
+      return memory_block['size']
+    return None
+
   def FindMemoryBlock(self, path):
     """Find memory block with given path.