[SuperSize] HTML Viewer: Fix Method Count under diff mode.

Under diff mode, previously the HTML Viewer would report very large
method (delta) counts. This was caused by the Python code assigning a
delta count of 1 (instead of 0) for changed symbols. Moreover, to
support delta count of 0, the JavaScript code change needs to be
updated to read it (i.e., cannot use "||" to assign defaults).

This CL fixes the above problems. Moreover, to reduce .ndjson file
size, 0 is used as the default symbol count under diff mode (1 is still
the defalut if one .size file is used to generate the .ndjson file).

Bug: 884985
Change-Id: I8038f8b8298073c8ced5ccf9100cf9911e533861
Reviewed-on: https://chromium-review.googlesource.com/1246280Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594431}

tools/binary_size/libsupersize/html_report.py

@@ -112,6 +112,9 @@ def _MakeTreeViewList(symbols, include_all_symbols):
   small_symbol_pss = collections.defaultdict(
       lambda: collections.defaultdict(float))
 
+  # For delta symbols, most counts should 0, so use that as default. Else use 1.
+  default_symbol_count = 0 if symbols.IsDelta() else 1
+
   if include_all_symbols:
     main_symbols, extra_symbols = symbols, []
   else:
@@ -124,9 +127,9 @@ def _MakeTreeViewList(symbols, include_all_symbols):
     symbol_size = round(symbol.pss, 2)
     if symbol_size.is_integer():
       symbol_size = int(symbol_size)
-    symbol_count = 1
-    if symbol.IsDelta() and symbol.diff_status == models.DIFF_STATUS_REMOVED:
-      symbol_count = -1
+    symbol_count = default_symbol_count
+    if symbol.IsDelta():
+      symbol_count = models.DIFF_COUNT_DELTA[symbol.diff_status]
 
     path = symbol.source_path or symbol.object_path
     file_node = _GetOrAddFileNode(
@@ -146,7 +149,7 @@ def _MakeTreeViewList(symbols, include_all_symbols):
     # count as -1 rather than the default, 1.
     # We don't care about accurate counts for other symbol types currently,
     # so this data is only included for methods.
-    if is_dex_method and symbol_count != 1:
+    if is_dex_method and symbol_count != default_symbol_count:
       symbol_entry[_COMPACT_SYMBOL_COUNT_KEY] = symbol_count
     if symbol.flags:
       symbol_entry[_COMPACT_SYMBOL_FLAGS_KEY] = symbol.flags

tools/binary_size/libsupersize/models.py

@@ -152,6 +152,7 @@ DIFF_STATUS_CHANGED = 1
 DIFF_STATUS_ADDED = 2
 DIFF_STATUS_REMOVED = 3
 DIFF_PREFIX_BY_STATUS = ['= ', '~ ', '+ ', '- ']
+DIFF_COUNT_DELTA = [0, 0, 1, -1]
 
 
 STRING_LITERAL_NAME = 'string literal'

tools/binary_size/libsupersize/static/tree-worker.js

@@ -361,8 +361,9 @@ class TreeBuilder {
    * tree nodes for that file's symbols attached. Afterwards attach that node to
    * its parent directory node, or create it if missing.
    * @param {FileEntry} fileEntry File entry from data file
+   * @param {boolean} diffMode Whether diff mode is in effect.
    */
-  addFileEntry(fileEntry) {
+  addFileEntry(fileEntry, diffMode) {
     const idPath = this._getPath(fileEntry);
     // make node for this
     const fileNode = createNode({
@@ -370,13 +371,15 @@ class TreeBuilder {
       shortNameIndex: lastIndexOf(idPath, this._sep) + 1,
       type: _CONTAINER_TYPES.FILE,
     });
+    const defaultCount = diffMode ? 0 : 1;
     // build child nodes for this file's symbols and attach to self
     for (const symbol of fileEntry[_KEYS.FILE_SYMBOLS]) {
       const size = symbol[_KEYS.SIZE];
       const type = symbol[_KEYS.TYPE];
-      const count = symbol[_KEYS.COUNT] || 1;
-      const flags = symbol[_KEYS.FLAGS] || 0;
-      const numAliases = symbol[_KEYS.NUM_ALIASES] || 1;
+      const count = _KEYS.COUNT in symbol ? symbol[_KEYS.COUNT] : defaultCount;
+      const flags = _KEYS.FLAGS in symbol ? symbol[_KEYS.FLAGS] : 0;
+      const numAliases =
+          _KEYS.NUM_ALIASES in symbol ? symbol[_KEYS.NUM_ALIASES] : 1;
 
       const symbolNode = createNode({
         // Join file path to symbol name with a ":"
@@ -758,13 +761,15 @@ async function buildTree(groupBy, filterTest, highlightTest, onProgress) {
   try {
     // Post partial state every second
     let lastBatchSent = Date.now();
+    let diffMode = null;
     for await (const dataObj of fetcher.newlineDelimtedJsonStream()) {
       if (meta == null) {
         // First line of data is used to store meta information.
         meta = /** @type {Meta} */ (dataObj);
+        diffMode = meta.diff_mode;
         postToUi();
       } else {
-        builder.addFileEntry(/** @type {FileEntry} */ (dataObj));
+        builder.addFileEntry(/** @type {FileEntry} */ (dataObj), diffMode);
         const currentTime = Date.now();
         if (currentTime - lastBatchSent > 500) {
           postToUi();