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..dae06514377e2b5fd6fbbbf44f446b10c5676249 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.

[Alexei Svitkine (slow), 2014/07/21 20:25:35]

I guess this is still OK if you really want to support a default percentage on
first run after install. Otherwise, I'd still advise doing things entirely from
the server-side.

[Not at Google. Contact bengr, 2014/07/21 21:45:09]

Acknowledged.

+void DataCompressionProxyBaseFieldTrial(
+    const char* trial_name,

[Alexei Svitkine (slow), 2014/07/21 20:25:35]

Nit: Might as well make this a const std::string& here - no advantage to keeping
it a C string since it will be converted below anyway.

[Not at Google. Contact bengr, 2014/07/21 21:45:08]

Done.

+    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, 2020. By default, disabled.

[Alexei Svitkine (slow), 2014/07/21 20:25:35]

2020 is too far away. How about 2016 for now?

[Not at Google. Contact bengr, 2014/07/21 21:45:08]

Done.

+  scoped_refptr<base::FieldTrial> trial(
+      base::FieldTrialList::FactoryGetFieldTrial(
+          trial_name,
+          total_probability,
+          kDisabled, 2020, 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;
+}
+
+void DataCompressionProxyFieldTrials() {
+  // 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

[Alexei Svitkine (slow), 2014/07/21 20:25:35]

Do we have the promo UI on all platforms already?

[Not at Google. Contact bengr, 2014/07/21 21:45:09]

No. Currently, this is not used on desktop and ChromeOS.

[Alexei Svitkine (slow), 2014/07/22 13:48:23]

Then it seems incorrect to set up a trial with 10% active group for this on all
platforms here, given that it's not implemented everywhere.

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

The intention was that the trial would automatically be picked up when we
launched on more platforms. There isn't currently a good place to define the
common method DataCompressionProxyBaseFieldTrial(...) used to set up both
trials. While I could add a new data reduction proxy specific file, it seems we
will still have unused trials when we do this for desktop and not ChromeOS, so
didn't think it was worth it. Let me know if you prefer this, or if you have any
alternative suggestions.

[Alexei Svitkine (slow), 2014/07/23 14:35:26]

Can you specify a default percentage of 0 on platforms that don't have the promo
code wired up yet? You can do it via a small ifdef in this code.

The other possibility is to keep the first-run config in the client code around
only for mobile, where presumably first run is more important. Do we really need
first run configs in the client code for other platforms? Is the promo on those
platforms only going to be shown on first run? (I would hope not, since that
would ignore the majority of existing users.)

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

We decided to remove the trial for rollout, so that simplified things. Moved
this code back to mobile, and removed the rollout trial all together. 

+  // 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();
+  DataCompressionProxyFieldTrials();

[Alexei Svitkine (slow), 2014/07/21 20:25:35]

Nit: Rename to SetupDataCompressionProxyFieldTrials().

[Not at Google. Contact bengr, 2014/07/21 21:45:09]

Done.

 
 #if defined(OS_ANDROID) || defined(OS_IOS)
   chrome::SetupMobileFieldTrials(parsed_command_line_);