Use better group names for zram field trial

chrome/browser/chromeos/chrome_browser_main_chromeos.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/chrome_browser_main_chromeos.h"
 
 #include <string>
 #include <vector>
 
 #include "ash/shell.h"
@@ skipping 762 matching lines @@
   // number is stored in a file.
   const FilePath kZramGroupPath("/home/chronos/.swap_exp_enrolled");
   std::string zram_file_content;
   // If the file does not exist, the experiment has not started.
   if (!file_util::ReadFileToString(kZramGroupPath, &zram_file_content))
     return;
   // The file contains a single significant character, possibly followed by
   // newline.  "x" means the user has opted out.  "0" through "8" are the valid
   // group names.  (See src/platform/init/swap-exp.conf in chromiumos repo for
   // group meanings.)
-  std::string zram_group = zram_file_content.substr(0, 1);
-  if (zram_group.compare("x") == 0)
+  if (zram_file_content.empty()) {
+    LOG(WARNING) << "zram field trial: " << kZramGroupPath << " is empty";
     return;
+  }
+  char zram_group = zram_file_content[0];
+  if (zram_group == 'x')
+    return;
+  if (zram_group < '0' || zram_group > '8') {
+    LOG(WARNING) << "zram field trial: invalid group \"" << zram_group << "\"";
+    return;
+  }
+  LOG(WARNING) << "zram field trial: group " << zram_group;
   const base::FieldTrial::Probability kDivisor = 1;  // on/off only
   scoped_refptr<base::FieldTrial> trial =
       base::FieldTrialList::FactoryGetFieldTrial(
           "ZRAM", kDivisor, "default", 2013, 12, 31, NULL);
   // Assign probability of 1 to the group Chrome OS has picked.  Assign 0 to
   // all other choices.
-  const char* const kGroups[] = { "0", "1", "2", "3", "4", "5", "6", "7", "8" };
-  bool matched = false;
-  for (size_t i = 0; i < arraysize(kGroups); ++i) {
-    bool match = zram_group.compare(kGroups[i]) == 0;
-    trial->AppendGroup(kGroups[i], match ? 1 : 0);
-    if (match) {
-      matched = true;
-      LOG(WARNING) << "zram field trial: group " << kGroups[i];
-    }
-  }
-  if (!matched)
-    LOG(WARNING) << "zram field trial: invalid group \"" << zram_group << "\"";
+  trial->AppendGroup("2GB RAM, no swap", zram_group == '0' ? 1 : 0);

[Alexei Svitkine (slow), 2013/01/09 19:22:06]

Can you make the group names not have spaces and commas (and other special
chars)? You can use underscores for example.

(I'm not sure if it's a problem in practice, but no other trials use them I
think, so it's safer not to).

[Luigi Semenzato, 2013/01/09 19:25:31]

Done.

+  trial->AppendGroup("2GB RAM, 2GB swap", zram_group == '1' ? 1 : 0);
+  trial->AppendGroup("2GB RAM, 3GB swap", zram_group == '2' ? 1 : 0);
+  trial->AppendGroup("4GB RAM, no swap", zram_group == '3' ? 1 : 0);
+  trial->AppendGroup("4GB RAM, 4GB swap", zram_group == '4' ? 1 : 0);
+  trial->AppendGroup("4GB RAM, 6GB swap", zram_group == '5' ? 1 : 0);
+  trial->AppendGroup("snow, no swap", zram_group == '6' ? 1 : 0);
+  trial->AppendGroup("snow, 1GB swap", zram_group == '7' ? 1 : 0);
+  trial->AppendGroup("snow, 2GB swap", zram_group == '8' ? 1 : 0);
 }
 
 }  //  namespace chromeos