Construct a field trial to see if HIGH or MEDIUM memory model "works better"

Includes definition of a FieldTrial class to support this.
I have thoughts in my head about how this will eventually
extend to be controllable via UMA (as well as being able
to run tests defined at compile time, as was done in this
example.


r=mbelshe, mmentovai
Review URL: http://codereview.chromium.org/7638

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@3604 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 1 deletions

diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index 9ff0b7b..d4aabe7 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -5,9 +5,10 @@
 #include "chrome/browser/browser_process_impl.h"
 
 #include "base/command_line.h"
-#include "base/thread.h"
 #include "base/path_service.h"
+#include "base/thread.h"
 #include "chrome/browser/automation/automation_provider_list.h"
+#include "chrome/browser/browser_trial.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/download/download_file.h"
 #include "chrome/browser/download/save_file_manager.h"
@@ -115,6 +116,16 @@ BrowserProcessImpl::BrowserProcessImpl(CommandLine& command_line)
       else if (model == L"medium")
         memory_model_ = MEDIUM_MEMORY_MODEL;
     }
+  } else {
+    // Randomly choose what memory model to use.
+    const double probability = 0.5;
+    FieldTrial* trial(new FieldTrial(BrowserTrial::kMemoryModelFieldTrial,
+                                     probability));
+    DCHECK(FieldTrialList::Find(BrowserTrial::kMemoryModelFieldTrial) == trial);
+    if (trial->boolean_value())
+      memory_model_ = HIGH_MEMORY_MODEL;
+    else
+      memory_model_ = MEDIUM_MEMORY_MODEL;
   }
 
   suspend_controller_ = new SuspendController();