Bug 1408279 - Make profile JSON easier to read. r=mstange.

Currently the choices of SingleLineStyle and MultiLineStyle are sub-optimal,
which makes debugging of profiles difficult.

- A large chunk of the profile is put on a single line, which is very hard to
  read in a text editor.

- Other short and repetitive constructs are unnecessarily spread across
  multiple lines.

This patch makes things more readable.

tools/profiler/core/ProfileBufferEntry.cpp

@@ -87,7 +87,8 @@ public:
    : mWriter(aWriter)
    , mIndex(0)
   {
-    aWriter.StartObjectProperty("schema");
+    aWriter.StartObjectProperty("schema",
+                                SpliceableJSONWriter::SingleLineStyle);
   }
 
   void WriteField(const char* aName) {
@@ -187,7 +188,7 @@ public:
     , mStrings(&aStrings)
     , mNextFreeIndex(0)
   {
-    mJSONWriter.StartArrayElement();
+    mJSONWriter.StartArrayElement(SpliceableJSONWriter::SingleLineStyle);
   }
 
   // If you don't have access to a UniqueStrings, you had better not try and
@@ -197,7 +198,7 @@ public:
     , mStrings(nullptr)
     , mNextFreeIndex(0)
   {
-    mJSONWriter.StartArrayElement();
+    mJSONWriter.StartArrayElement(SpliceableJSONWriter::SingleLineStyle);
   }
 
   ~AutoArraySchemaWriter() {
@@ -938,7 +939,7 @@ static void
 AddPausedRange(SpliceableJSONWriter& aWriter, const char* aReason,
                const Maybe<double>& aStartTime, const Maybe<double>& aEndTime)
 {
-  aWriter.Start(SpliceableJSONWriter::SingleLineStyle);
+  aWriter.Start();
   if (aStartTime) {
     aWriter.DoubleProperty("startTime", *aStartTime);
   } else {

tools/profiler/core/ProfileJSONWriter.h

@@ -85,7 +85,7 @@ public:
     : JSONWriter(mozilla::Move(aWriter))
   { }
 
-  void StartBareList(CollectionStyle aStyle = SingleLineStyle) {
+  void StartBareList(CollectionStyle aStyle = MultiLineStyle) {
     StartCollection(nullptr, "", aStyle);
   }
 

tools/profiler/core/ProfilerMarker.h

@@ -51,7 +51,7 @@ public:
       // if have location data
       //   b.NameValue(marker, "location", ...);
       if (mPayload) {
-        aWriter.StartObjectElement();
+        aWriter.StartObjectElement(SpliceableJSONWriter::SingleLineStyle);
         {
           mPayload->StreamPayload(aWriter, aProcessStartTime, aUniqueStacks);
         }

tools/profiler/core/ThreadInfo.cpp

@@ -82,7 +82,7 @@ ThreadInfo::StreamJSON(const ProfileBuffer& aBuffer,
 
   double firstSampleTime = 0.0;
 
-  aWriter.Start(SpliceableJSONWriter::SingleLineStyle);
+  aWriter.Start();
   {
     StreamSamplesAndMarkers(Name(), ThreadId(), aBuffer, aWriter,
                             aProcessStartTime,

tools/profiler/core/platform.cpp

@@ -1670,8 +1670,7 @@ locked_profiler_stream_json_for_this_process(PSLockRef aLock,
   }
   aWriter.EndArray();
 
-  aWriter.StartArrayProperty("pausedRanges",
-                             SpliceableJSONWriter::SingleLineStyle);
+  aWriter.StartArrayProperty("pausedRanges");
   {
     buffer.StreamPausedRangesToJSON(aWriter, aSinceTime);
   }
@@ -2449,7 +2448,7 @@ profiler_get_profile(double aSinceTime, bool aIsShuttingDown)
   MOZ_RELEASE_ASSERT(CorePS::Exists());
 
   SpliceableChunkedJSONWriter b;
-  b.Start(SpliceableJSONWriter::SingleLineStyle);
+  b.Start();
   {
     if (!profiler_stream_json_for_this_process(b, aSinceTime,
                                                aIsShuttingDown)) {
@@ -2571,7 +2570,7 @@ locked_profiler_save_profile_to_file(PSLockRef aLock, const char* aFilename,
   stream.open(aFilename);
   if (stream.is_open()) {
     SpliceableJSONWriter w(MakeUnique<OStreamJSONWriteFunc>(stream));
-    w.Start(SpliceableJSONWriter::SingleLineStyle);
+    w.Start();
     {
       locked_profiler_stream_json_for_this_process(aLock, w, /* sinceTime */ 0,
                                                    aIsShuttingDown);

tools/profiler/gecko/nsProfiler.cpp

@@ -591,7 +591,7 @@ nsProfiler::StartGathering(double aSinceTime)
   TimeStamp thisProcessFirstSampleTime;
 
   // Start building up the JSON result and grab the profile from this process.
-  mWriter->Start(SpliceableJSONWriter::SingleLineStyle);
+  mWriter->Start();
   if (!profiler_stream_json_for_this_process(*mWriter, aSinceTime,
                                              /* aIsShuttingDown */ true,
                                              &thisProcessFirstSampleTime)) {

tools/profiler/tests/gtest/GeckoProfiler.cpp

@@ -628,7 +628,7 @@ TEST(GeckoProfiler, StreamJSONForThisProcess)
   profiler_start(PROFILER_DEFAULT_ENTRIES, PROFILER_DEFAULT_INTERVAL,
                  features, filters, MOZ_ARRAY_LENGTH(filters));
 
-  w.Start(SpliceableJSONWriter::SingleLineStyle);
+  w.Start();
   ASSERT_TRUE(profiler_stream_json_for_this_process(w));
   w.End();
 
@@ -663,7 +663,7 @@ TEST(GeckoProfiler, StreamJSONForThisProcessThreaded)
     NS_NewRunnableFunction(
       "GeckoProfiler_StreamJSONForThisProcessThreaded_Test::TestBody",
       [&]() {
-        w.Start(SpliceableJSONWriter::SingleLineStyle);
+        w.Start();
         ASSERT_TRUE(profiler_stream_json_for_this_process(w));
         w.End();
       }),