Tweak output of (memcheck|drmemory)_analyze.py.

Wrap error reports in "### (BEGIN|END) MEMORY TOOL REPORT". This will allow us
to extract them with GTestLogParser and use them as snippets.

BUG=453020
R=thestig@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/884813002

Cr-Commit-Position: refs/heads/master@{#313572}

tools/valgrind/drmemory_analyze.py

@@ -40,13 +40,18 @@ class DrMemoryError:
     self._suppression = "\n".join(supp_lines)
 
   def __str__(self):
-    output = self._report + "\n"
+    output = ""
+    output += "### BEGIN MEMORY TOOL REPORT (error hash=#%016X#)\n" %
+        self.ErrorHash()
+    output += self._report + "\n"
     if self._testcase:
       output += "The report came from the `%s` test.\n" % self._testcase
     output += "Suppression (error hash=#%016X#):\n" % self.ErrorHash()
     output += ("  For more info on using suppressions see "
         "http://dev.chromium.org/developers/how-tos/using-drmemory#TOC-Suppressing-error-reports-from-the-\n")
     output += "{\n%s\n}\n" % self._suppression
+    output += "### END MEMORY TOOL REPORT (error hash=#%016X#)\n" %
+        self.ErrorHash()
     return output
 
   # This is a device-independent hash identifying the suppression.

tools/valgrind/memcheck_analyze.py

@@ -231,6 +231,9 @@ class ValgrindError:
     ''' Pretty print the type and backtrace(s) of this specific error,
         including suppression (which is just a mangled backtrace).'''
     output = ""
+    output += "\n" # Make sure the ### is at the beginning of line.
+    output += "### BEGIN MEMORY TOOL REPORT (error hash=#%016X#)\n" %
+        self.ErrorHash()
     if (self._commandline):
       output += self._commandline + "\n"
 
@@ -327,6 +330,8 @@ class ValgrindError:
         supplines[frame] = "*".join(m.groups())
 
     output += "\n".join(supplines) + "\n"
+    output += "### END MEMORY TOOL REPORT (error hash=#%016X#)\n" %
+        self.ErrorHash()
 
     return output