Add field trial for the WebAPK server URL

chrome/browser/android/webapk/webapk_installer.cc

Index: chrome/browser/android/webapk/webapk_installer.cc
diff --git a/chrome/browser/android/webapk/webapk_installer.cc b/chrome/browser/android/webapk/webapk_installer.cc
index 000f98c538baa5e75f3316ae58d3afc63064c3e3..ba1495d8db680ca1e1fec995f5f5c4f48589e7e0 100644
--- a/chrome/browser/android/webapk/webapk_installer.cc
+++ b/chrome/browser/android/webapk/webapk_installer.cc
@@ -22,7 +22,9 @@
 #include "chrome/browser/android/webapk/webapk.pb.h"
 #include "chrome/browser/android/webapk/webapk_icon_hasher.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_switches.h"
+#include "components/variations/variations_associated_data.h"
 #include "components/version_info/version_info.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/manifest_util.h"
@@ -35,9 +37,12 @@
 namespace {
 
 // The default WebAPK server URL.
-const char kDefaultWebApkServerUrl[] =
+const char kDefaultServerUrl[] =
     "https://webapk.googleapis.com/v1alpha/webApks/?alt=proto";
 
+// Flag for setting the WebAPK server URL.
+const char kServerUrlVariationsParamKey[] = "ServerUrl";
+
 // The MIME type of the POST data sent to the server.
 const char kProtoMimeType[] = "application/x-protobuf";
 
@@ -53,6 +58,17 @@ const int kWorldReadableFilePermission = base::FILE_PERMISSION_READ_BY_USER |
                                          base::FILE_PERMISSION_READ_BY_GROUP |
                                          base::FILE_PERMISSION_READ_BY_OTHERS;
 
+// Returns the WebAPK server URL based on the command line flags and the
+// currently active field trials.
+GURL GetServerUrl() {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kWebApkServerUrl))
+    return GURL(command_line->GetSwitchValueASCII(switches::kWebApkServerUrl));

[dominickn, 2016/10/24 00:32:37]

For safety, should you test whether this GURL is_valid() and return the empty
GURL if so? And then don't initiate the network request if the URL is no good?

[pkotwicz, 2016/10/24 04:33:42]

Good point.

UrlFetcher crashes if given an invalid URL

+  std::string server_url = variations::GetVariationParamValueByFeature(
+      features::kWebApk, kServerUrlVariationsParamKey);
+  return GURL(!server_url.empty() ? server_url : kDefaultServerUrl);
+}
+
 // Returns the scope from |info| if it is specified. Otherwise, returns the
 // default scope.
 GURL GetScope(const ShortcutInfo& info) {
@@ -160,15 +176,11 @@ WebApkInstaller::WebApkInstaller(const ShortcutInfo& shortcut_info,
                                  const SkBitmap& shortcut_icon)
     : shortcut_info_(shortcut_info),
       shortcut_icon_(shortcut_icon),
+      server_url_(GetServerUrl()),
       webapk_download_url_timeout_ms_(kWebApkDownloadUrlTimeoutMs),
       download_timeout_ms_(kDownloadTimeoutMs),
       task_type_(UNDEFINED),
       weak_ptr_factory_(this) {
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  server_url_ =
-      GURL(command_line->HasSwitch(switches::kWebApkServerUrl)
-               ? command_line->GetSwitchValueASCII(switches::kWebApkServerUrl)
-               : kDefaultWebApkServerUrl);
   CreateJavaRef();
 }