[tracing] Adding task information to heap profiler

base/trace_event/heap_profiler_type_name_deduplicator.cc

Index: base/trace_event/heap_profiler_type_name_deduplicator.cc
diff --git a/base/trace_event/heap_profiler_type_name_deduplicator.cc b/base/trace_event/heap_profiler_type_name_deduplicator.cc
index e7f57c8ae0ebd853404eb3bfd2da792d8547b05a..da4dc0d11f14d80a35f7a51c0e47b48c6f5d53a2 100644
--- a/base/trace_event/heap_profiler_type_name_deduplicator.cc
+++ b/base/trace_event/heap_profiler_type_name_deduplicator.cc
@@ -9,6 +9,7 @@
 #include <string>
 #include <utility>
 
+#include "base/files/file_path.h"
 #include "base/json/string_escape.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event_memory_overhead.h"
@@ -16,6 +17,32 @@
 namespace base {
 namespace trace_event {
 
+namespace {
+
+// Extract category name from the file name.
+StringPiece ExtractDirNameFromTaskContext(const char* type_name) {

[petrcermak, 2016/03/29 12:49:05]

The comment, method name and argument name all disagree with each other:

"file name" vs. "TaskContext" vs. "type_name"
"category name" vs. "DirName"

[ssid, 2016/03/29 18:32:45]

wdyt now?

[petrcermak, 2016/03/29 18:42:13]

I think it's much better, but the comment is now "begging" for an "Otherwise,
..." sentence (what if |type_name| is not task context). Also s/was/is/ (makes
it sound less improbable).

[ssid, 2016/03/29 23:04:18]

Done.

+  StringPiece result = type_name;
+  size_t last_seperator = result.find_last_of(FilePath::kSeparators);
+
+  // If |type_name| is a not a file path the seperator will not be found.

[petrcermak, 2016/03/29 12:49:05]

nit: add a comma after "path"

[ssid, 2016/03/29 18:32:45]

Done.

+  // return the type name.

[petrcermak, 2016/03/29 12:49:05]

This is not a sentence, I suggest merging it with the first sentence:

"... not be found, so the whole type name is returned."

[ssid, 2016/03/29 18:32:45]

Done.

+  if (last_seperator == StringPiece::npos)
+    return result;
+
+  // Remove the file name from the path.
+  result.remove_suffix(result.length() - last_seperator);
+
+  // Remove the parent directory references - '..'.
+  while (result.starts_with(FilePath::kParentDirectory)) {
+    size_t parent_seperator = result.find_first_of(FilePath::kSeparators);
+    DCHECK_NE(StringPiece::npos, parent_seperator);
+    result.remove_prefix(parent_seperator + 1);
+  }
+  return result;
+}
+
+}  // namespace
+
 TypeNameDeduplicator::TypeNameDeduplicator() {
   // A null pointer has type ID 0 ("unknown type");
   type_ids_.insert(std::make_pair(nullptr, 0));
@@ -53,9 +80,12 @@ void TypeNameDeduplicator::AppendAsTraceFormat(std::string* out) const {
     // a dictionary.
     SStringPrintf(&buffer, ",\"%d\":", it->second);
 
+    // TODO(ssid): crbug.com/594803 the type name is misused for category name.
+    StringPiece type_info = ExtractDirNameFromTaskContext(it->first);
+
     // |EscapeJSONString| appends, it does not overwrite |buffer|.
     bool put_in_quotes = true;
-    EscapeJSONString(it->first, put_in_quotes, &buffer);
+    EscapeJSONString(type_info, put_in_quotes, &buffer);
     out->append(buffer);
   }