Add a chrome://flags entry for kProcessSharingWithStrictSiteInstances

Bug: 928390
Change-Id: If3ad1ee79805b328415c8fc5bd65a0f8516dad8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1585143Reviewed-by: Nate Chapin <japhet@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654558}

chrome/browser/about_flags.cc

@@ -1644,6 +1644,11 @@ const FeatureEntry kFeatureEntries[] = {
     {"enable-site-per-process", flag_descriptions::kStrictSiteIsolationName,
      flag_descriptions::kStrictSiteIsolationDescription, kOsAndroid,
      SINGLE_VALUE_TYPE(switches::kSitePerProcess)},
+    {"enable-process-sharing-with-strict-site-instances",
+     flag_descriptions::kProcessSharingWithStrictSiteInstancesName,
+     flag_descriptions::kProcessSharingWithStrictSiteInstancesDescription,
+     kOsAndroid,
+     FEATURE_VALUE_TYPE(features::kProcessSharingWithStrictSiteInstances)},
 #endif
     {"isolate-origins", flag_descriptions::kIsolateOriginsName,
      flag_descriptions::kIsolateOriginsDescription, kOsAll,

chrome/browser/flag-metadata.json

@@ -1475,6 +1475,11 @@
     "owners": [ "//components/data_reduction_proxy/OWNERS" ],
     "expiry_milestone": 76
   },
+  {
+    "name": "enable-process-sharing-with-strict-site-instances",
+    "owners": [ "japhet" ],
+    "expiry_milestone": 80
+  },
   {
     "name": "enable-query-in-omnibox",
     "owners": [ "tommycli", "chrome-omnibox-team@google.com" ],

chrome/browser/flag_descriptions.cc

@@ -2627,6 +2627,18 @@ const char kStrictSiteIsolationDescription[] =
     "#site-isolation-trial-opt-out for how to disable site isolation for "
     "testing.";
 
+extern const char kProcessSharingWithStrictSiteInstancesName[] =
+    "Process sharing with strict site instances";
+extern const char kProcessSharingWithStrictSiteInstancesDescription[] =
+    "When site isolation is disabled, this mode changes how sites are lumped "
+    "in to a shared process. Process selection is usually controlled with "
+    "site instances. With strict site isolation, each site on a page gets its "
+    "own site instance and process. With site isolation disabled and without "
+    "this mode, all sites that share a process are put into the same site "
+    "instance. This mode adds a third way: site instances are strictly "
+    "separated like strict site isolation, but process selection puts multiple "
+    "site instances in a single process.";
+
 const char kTranslateAndroidManualTriggerName[] =
     "Enable manual translate trigger";
 const char kTranslateAndroidManualTriggerDescription[] =

chrome/browser/flag_descriptions.h

@@ -1563,6 +1563,9 @@ extern const char kSiteIsolationForPasswordSitesDescription[];
 extern const char kStrictSiteIsolationName[];
 extern const char kStrictSiteIsolationDescription[];
 
+extern const char kProcessSharingWithStrictSiteInstancesName[];
+extern const char kProcessSharingWithStrictSiteInstancesDescription[];
+
 extern const char kTranslateAndroidManualTriggerName[];
 extern const char kTranslateAndroidManualTriggerDescription[];
 

tools/metrics/histograms/enums.xml

@@ -32405,6 +32405,8 @@ Called by update_gpu_driver_bug_workaround_entries.py.-->
   <int value="-1907342706" label="ReadItLaterInMenu:disabled"/>
   <int value="-1903365454" label="SyncPseudoUSSPreferences:disabled"/>
   <int value="-1899715534" label="GamepadPollingInterval:enabled"/>
+  <int value="-1899409297"
+      label="ProcessSharingWithStrictSiteInstances:disabled"/>
   <int value="-1895719323" label="VrBrowsingTabsView:enabled"/>
   <int value="-1894699049" label="AudioFocusEnforcement:disabled"/>
   <int value="-1893668420"
@@ -35003,6 +35005,8 @@ from previous Chrome versions.
   <int value="2129929643" label="enable-use-zoom-for-dsf"/>
   <int value="2134480727" label="MediaSessionAccelerators:disabled"/>
   <int value="2135408204" label="OverscrollHistoryNavigation:disabled"/>
+  <int value="2137113620"
+      label="ProcessSharingWithStrictSiteInstances:enabled"/>
   <int value="2137347307" label="enable-drive-apps-in-app-list"/>
   <int value="2137599770" label="enable-win32k-renderer-lockdown"/>
   <int value="2138146331" label="OmniboxVoiceSearchAlwaysVisible:enabled"/>