Split the field trial setup code into desktop and mobile files.

chrome/browser/chrome_browser_field_trials_mobile.cc

+// Copyright 2013 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/chrome_browser_field_trials_mobile.h"
+
+#include <string>
+
+#include "base/command_line.h"
+#include "base/metrics/field_trial.h"
+#include "base/prefs/pref_service.h"
+#include "chrome/common/chrome_version_info.h"
+
+namespace chrome {
+
+namespace {
+
+// Governs the rollout of the compression proxy for Chrome on mobile platforms.
+// Always enabled in DEV and BETA versions.
+// Stable percentage will be controlled from server.
+void DataCompressionProxyFieldTrial() {
+  const char kDataCompressionProxyFieldTrialName[] =
+      "DataCompressionProxyRollout";
+  const base::FieldTrial::Probability kDataCompressionProxyDivisor = 1000;
+
+  // 10/1000 = 1% for starters.
+  const base::FieldTrial::Probability kDataCompressionProxyStable = 10;
+  const char kEnabled[] = "Enabled";
+  const char kDisabled[] = "Disabled";
+
+  // Find out if this is a stable channel.
+  const bool kIsStableChannel =
+      chrome::VersionInfo::GetChannel() == chrome::VersionInfo::CHANNEL_STABLE;
+
+  // Experiment enabled until Jan 1, 2015. By default, disabled.
+  scoped_refptr<base::FieldTrial> trial(
+      base::FieldTrialList::FactoryGetFieldTrial(
+          kDataCompressionProxyFieldTrialName, kDataCompressionProxyDivisor,
+          kDisabled, 2015, 1, 1, NULL));
+
+  // We want our trial results to be persistent.
+  trial->UseOneTimeRandomization();
+  // Non-stable channels will run with probability 1.
+  const int kEnabledGroup = trial->AppendGroup(
+      kEnabled,
+      kIsStableChannel ?
+          kDataCompressionProxyStable : kDataCompressionProxyDivisor);
+
+  const int v = trial->group();
+  VLOG(1) << "DataCompression proxy enabled group id: " << kEnabledGroup
+          << ". Selected group id: " << v;
+}
+
+}  // end namespace
+
+
+void SetupMobileFieldTrials(const CommandLine& parsed_command_line,
+                            const base::Time& install_time,
+                            PrefService* local_state) {
+  DataCompressionProxyFieldTrial();
+}
+
+}  // end namespace chrome