DMP: Add mmap-partition-alloc

Split the usage of Parition Alloc from mmap-catch-all. Partition Alloc
is the allocator used in Blink, and it would be helpful if we could see
the usage of this separately.

NOTRY=true

Review URL: https://codereview.chromium.org/423793003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285877 0039d316-1c4b-4281-b951-d872f2087c98

tools/deep_memory_profiler/policy.l2.json

@@ -24,6 +24,7 @@
     "mmap-gpu-transfer-ringbuffer",
     "mmap-gpu-gles2-createbuffer",
     "mmap-skia-font",
+    "mmap-partition-alloc",
     "mmap-catch-all",
     "tc-webcore-cachedmatchedproperties",
     "tc-webcore-fontcache",
@@ -195,6 +196,11 @@
       "stacktrace": ".*SkTypeface::openStream.*",
       "allocator": "mmap"
     },
+    {
+      "name": "mmap-partition-alloc",
+      "stacktrace": ".*WTF::partitionAllocSlowPath.*",
+      "allocator": "mmap"
+    },
     {
       "name": "mmap-catch-all",
       "stacktrace": ".*",