Apply chrome://flags/#force-ui-direction to AppKit.

Bug: 820348
Change-Id: Id9c8ff9878f6595f99d4630a18aa023b55cc8467
Reviewed-on: https://chromium-review.googlesource.com/956297Reviewed-by: Jungshik Shin <jshin@chromium.org>
Reviewed-by: Leonard Grey <lgrey@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Sidney San Martín <sdy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542995}

base/i18n/rtl.cc

@@ -84,30 +84,6 @@ base::i18n::TextDirection GetCharacterDirection(UChar32 character) {
   return base::i18n::UNKNOWN_DIRECTION;
 }
 
-// Gets the explicitly forced text direction for debugging. If no forcing is
-// applied, returns UNKNOWN_DIRECTION.
-base::i18n::TextDirection GetForcedTextDirection() {
-  // On iOS, check for RTL forcing.
-#if defined(OS_IOS)
-  if (base::ios::IsInForcedRTL())
-    return base::i18n::RIGHT_TO_LEFT;
-#endif
-
-  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  if (command_line->HasSwitch(switches::kForceUIDirection)) {
-    std::string force_flag =
-        command_line->GetSwitchValueASCII(switches::kForceUIDirection);
-
-    if (force_flag == switches::kForceDirectionLTR)
-      return base::i18n::LEFT_TO_RIGHT;
-
-    if (force_flag == switches::kForceDirectionRTL)
-      return base::i18n::RIGHT_TO_LEFT;
-  }
-
-  return base::i18n::UNKNOWN_DIRECTION;
-}
-
 }  // namespace
 
 namespace base {
@@ -186,6 +162,28 @@ bool ICUIsRTL() {
   return g_icu_text_direction == RIGHT_TO_LEFT;
 }
 
+TextDirection GetForcedTextDirection() {
+// On iOS, check for RTL forcing.
+#if defined(OS_IOS)
+  if (base::ios::IsInForcedRTL())
+    return base::i18n::RIGHT_TO_LEFT;
+#endif
+
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kForceUIDirection)) {
+    std::string force_flag =
+        command_line->GetSwitchValueASCII(switches::kForceUIDirection);
+
+    if (force_flag == switches::kForceDirectionLTR)
+      return base::i18n::LEFT_TO_RIGHT;
+
+    if (force_flag == switches::kForceDirectionRTL)
+      return base::i18n::RIGHT_TO_LEFT;
+  }
+
+  return base::i18n::UNKNOWN_DIRECTION;
+}
+
 TextDirection GetTextDirectionForLocaleInStartUp(const char* locale_name) {
   // Check for direction forcing.
   TextDirection forced_direction = GetForcedTextDirection();

base/i18n/rtl.h

@@ -60,6 +60,10 @@ BASE_I18N_EXPORT bool IsRTL();
 // NOTE: Generally, you should call IsRTL() instead of this.
 BASE_I18N_EXPORT bool ICUIsRTL();
 
+// Gets the explicitly forced text direction for debugging. If no forcing is
+// applied, returns UNKNOWN_DIRECTION.
+BASE_I18N_EXPORT TextDirection GetForcedTextDirection();
+
 // Returns the text direction for |locale_name|.
 // As a startup optimization, this method checks the locale against a list of
 // Chrome-supported RTL locales.

chrome/browser/chrome_browser_application_mac.mm

@@ -13,6 +13,7 @@
 #include "base/trace_event/trace_event.h"
 #import "chrome/browser/app_controller_mac.h"
 #import "chrome/browser/mac/exception_processor.h"
+#include "chrome/browser/ui/cocoa/l10n_util.h"
 #include "chrome/common/chrome_switches.h"
 #include "components/crash/core/common/crash_key.h"
 #import "components/crash/core/common/objc_zombie.h"
@@ -48,6 +49,8 @@ void CancelTerminate() {
   ObjcEvilDoers::ZombieEnable(true, 10000);
 
   chrome::InstallObjcExceptionPreprocessor();
+
+  cocoa_l10n_util::ApplyForcedRTL();
 }
 
 - (id)init {

chrome/browser/ui/cocoa/l10n_util.h

@@ -50,6 +50,12 @@ bool ShouldDoExperimentalRTLLayout();
 // OSes would make Chrome stick out.
 bool ShouldFlipWindowControlsInRTL();
 
+// Set or clear the keys in NSUserDefaults which control UI direction based on
+// whether direction is forced by a Chrome flag. This should be early in
+// Chrome's launch, before any views or windows have been created, because it's
+// cached by AppKit.
+void ApplyForcedRTL();
+
 // Returns NSImageLeading when available (10.12+), otherwise
 // NSImageLeft for LTR and NSImageRight in RTL.
 NSCellImagePosition LeadingCellImagePosition();

chrome/browser/ui/cocoa/l10n_util.mm

@@ -94,6 +94,28 @@ bool ShouldFlipWindowControlsInRTL() {
   return ShouldDoExperimentalRTLLayout() && base::mac::IsAtLeastOS10_12();
 }
 
+void ApplyForcedRTL() {
+  NSUserDefaults* defaults = NSUserDefaults.standardUserDefaults;
+
+  // -registerDefaults: won't do the trick here because these defaults exist
+  // (in the global domain) to reflect the system locale. They need to be set
+  // in Chrome's domain to supersede the system value.
+  switch (base::i18n::GetForcedTextDirection()) {
+    case base::i18n::RIGHT_TO_LEFT:
+      [defaults setBool:YES forKey:@"AppleTextDirection"];
+      [defaults setBool:YES forKey:@"NSForceRightToLeftWritingDirection"];
+      break;
+    case base::i18n::LEFT_TO_RIGHT:
+      [defaults setBool:YES forKey:@"AppleTextDirection"];
+      [defaults setBool:NO forKey:@"NSForceRightToLeftWritingDirection"];
+      break;
+    default:
+      [defaults removeObjectForKey:@"AppleTextDirection"];
+      [defaults removeObjectForKey:@"NSForceRightToLeftWritingDirection"];
+      break;
+  }
+}
+
 // TODO(lgrey): Remove these when deployment target is 10.12.
 #if defined(MAC_OS_X_VERSION_10_12) && \
     (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12)