Add data reduction functionality to all platforms.

chrome/browser/chrome_browser_field_trials.cc

Index: chrome/browser/chrome_browser_field_trials.cc
diff --git a/chrome/browser/chrome_browser_field_trials.cc b/chrome/browser/chrome_browser_field_trials.cc
index 02640502b115c5418357b7789e65b5bdea66c676..172f9e2282c52f2c75ad829550becdabb4bf7cb8 100644
--- a/chrome/browser/chrome_browser_field_trials.cc
+++ b/chrome/browser/chrome_browser_field_trials.cc
@@ -31,6 +31,59 @@ ChromeBrowserFieldTrials::ChromeBrowserFieldTrials(
 ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() {
 }
 
+namespace {
+
+// Base function used by all data reduction proxy field trials. A trial is
+// only conducted for installs that are in the "Enabled" group. They are always
+// enabled on DEV and BETA channels, and for STABLE, a percentage will be
+// controlled from the server. Until the percentage is learned from the server,
+// a client-side configuration is used.

[Ryan Sleevi, 2014/07/22 01:56:30]

NACK on this. Use Finch, control it by the server. We need a killbit for this
level of experimentation.

[Not at Google. Contact bengr, 2014/07/22 23:03:52]

Finch experiments only kick in on the second run. This is a limitation of Finch.
Without this code, a user who expects this feature won't see it on first run. 

After the first run we do use Finch.

[Ryan Sleevi, 2014/07/23 00:54:44]

Conversely, there's no way we can turn this off for users, because they may
always fall in to the first run bucket.

From the bug, mdw@ said there were no plans for field trials, so I find this a
bit confusing. I do think we should err on the side of caution here, but if
there's a concern, perhaps following up on the launch bug (ergo for the sake of
discussion with privacy and finch teams) might be a productive exercise.

[Not at Google. Contact bengr, 2014/08/26 17:31:08]

Removed field trial for launch. Moved promo field trial back to mobile.

+void DataCompressionProxyBaseFieldTrial(
+    const std::string& trial_name,
+    const base::FieldTrial::Probability enabled_group_probability,
+    const base::FieldTrial::Probability total_probability) {
+  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, 2016. By default, disabled.
+  scoped_refptr<base::FieldTrial> trial(
+      base::FieldTrialList::FactoryGetFieldTrial(
+          trial_name,
+          total_probability,
+          kDisabled, 2016, 1, 1, base::FieldTrial::ONE_TIME_RANDOMIZED, NULL));
+
+  // Non-stable channels will run with probability 1.
+  const int kEnabledGroup = trial->AppendGroup(
+      kEnabled,
+      kIsStableChannel ? enabled_group_probability : total_probability);
+
+  const int v = trial->group();
+  VLOG(1) << trial_name <<  " enabled group id: " << kEnabledGroup
+          << ". Selected group id: " << v;

[Ryan Sleevi, 2014/07/23 00:54:43]

This is incredibly spammy, and isn't necessary in a Finch world of
server-controlled field trials (since you can determine experiment group via
chrome://version )

[Not at Google. Contact bengr, 2014/08/26 17:31:08]

Done.

+}
+
+void SetupDataCompressionProxyFieldTrials() {
+  // Governs the rollout of the compression proxy for Chrome on all platforms.
+  // In all channels, the percentage will be controlled from the server, and is
+  // configured to be 100% = 1000 / 1000 until overridden by the server.
+  DataCompressionProxyBaseFieldTrial(
+      "DataCompressionProxyRollout", 1000, 1000);
+
+  // Governs the rollout of the _promo_ for the compression proxy
+  // independently from the rollout of compression proxy. The enabled
+  // percentage is configured to be 10% = 100 / 1000 until overridden by the
+  // server. When this trial is "Enabled," users get a promo, whereas
+  // otherwise, compression is available without a promo.
+  DataCompressionProxyBaseFieldTrial(
+      "DataCompressionProxyPromoVisibility", 100, 1000);
+}
+
+}  // namespace
+
 void ChromeBrowserFieldTrials::SetupFieldTrials(const base::Time& install_time,
                                                 PrefService* local_state) {
   DCHECK(!install_time.is_null());
@@ -38,6 +91,7 @@ void ChromeBrowserFieldTrials::SetupFieldTrials(const base::Time& install_time,
   // Field trials that are shared by all platforms.
   chrome_variations::SetupUniformityFieldTrials(install_time);
   InstantiateDynamicTrials();
+  SetupDataCompressionProxyFieldTrials();
 
 #if defined(OS_ANDROID) || defined(OS_IOS)
   chrome::SetupMobileFieldTrials(parsed_command_line_);