Turn on the fixed position stacking context flag by default

Because there's an expectation that this flag will need to be reverted on a
branch, add both the enable and the disable flags so that only
web_contents_impl.cc will need to be touched to change the default value.
Both can be removed later, once this setting sticks.

BUG=none
TEST=none


Review URL: https://chromiumcodereview.appspot.com/10825027

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148572 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/about_flags.cc

@@ -106,6 +106,14 @@ const Experiment::Choice kOmniboxInlineHistoryQuickProviderChoices[] = {
     switches::kOmniboxInlineHistoryQuickProviderProhibited }
 };
 
+const Experiment::Choice kFixedPositionCreatesStackingContextChoices[] = {
+  { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", "" },
+  { IDS_GENERIC_EXPERIMENT_CHOICE_ENABLED,
+    switches::kEnableFixedPositionCreatesStackingContext, ""},
+  { IDS_GENERIC_EXPERIMENT_CHOICE_DISABLED,
+    switches::kDisableFixedPositionCreatesStackingContext, ""}
+};
+
 const Experiment::Choice kForceCompositingModeChoices[] = {
   { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", "" },
   { IDS_GENERIC_EXPERIMENT_CHOICE_ENABLED,
@@ -304,7 +312,7 @@ const Experiment kExperiments[] = {
     IDS_FLAGS_FIXED_POSITION_CREATES_STACKING_CONTEXT_NAME,
     IDS_FLAGS_FIXED_POSITION_CREATES_STACKING_CONTEXT_DESCRIPTION,
     kOsAll,
-    SINGLE_VALUE_TYPE(switches::kFixedPositionCreatesStackingContext)
+    MULTI_VALUE_TYPE(kFixedPositionCreatesStackingContextChoices)
   },
   // TODO(dspringer): When NaCl is on by default, remove this flag entry.
   {

content/browser/web_contents/web_contents_impl.cc

@@ -597,8 +597,8 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
     prefs.apply_default_device_scale_factor_in_compositor = true;
   }
 
-  prefs.fixed_position_creates_stacking_context =
-      command_line.HasSwitch(switches::kFixedPositionCreatesStackingContext);
+  prefs.fixed_position_creates_stacking_context = !command_line.HasSwitch(
+      switches::kDisableFixedPositionCreatesStackingContext);
 
   prefs.number_of_cpu_cores = base::SysInfo::NumberOfProcessors();
 

content/public/common/content_switches.cc

@@ -686,6 +686,9 @@ const char kDefaultTileHeight[]             = "default-tile-height";
 const char kMaxUntiledLayerWidth[]          = "max-untiled-layer-width";
 const char kMaxUntiledLayerHeight[]         = "max-untiled-layer-height";
 
-const char kFixedPositionCreatesStackingContext[]
-    = "fixed-position-creates-stacking-context";
+const char kEnableFixedPositionCreatesStackingContext[]
+    = "enable-fixed-position-creates-stacking-context";
+const char kDisableFixedPositionCreatesStackingContext[]
+    = "disable-fixed-position-creates-stacking-context";
+
 }  // namespace switches

content/public/common/content_switches.h

@@ -202,7 +202,8 @@ extern const char kDefaultTileWidth[];
 extern const char kDefaultTileHeight[];
 extern const char kMaxUntiledLayerWidth[];
 extern const char kMaxUntiledLayerHeight[];
-CONTENT_EXPORT extern const char kFixedPositionCreatesStackingContext[];
+CONTENT_EXPORT extern const char kEnableFixedPositionCreatesStackingContext[];
+CONTENT_EXPORT extern const char kDisableFixedPositionCreatesStackingContext[];
 
 extern const char kEnableVisualWordMovement[];