[rendertext,i18n] Added flag to force RTL rendering

base/i18n/rtl.cc

Index: base/i18n/rtl.cc
diff --git a/base/i18n/rtl.cc b/base/i18n/rtl.cc
index 095d66c6d8af13a9846e70ddc4fdf650410d2d03..e4ccc07159fc17c3fb631383b19d1b1b21fdb72d 100644
--- a/base/i18n/rtl.cc
+++ b/base/i18n/rtl.cc
@@ -55,6 +55,16 @@ std::string GetLocaleString(const icu::Locale& locale) {
 // directionality, returns UNKNOWN_DIRECTION if it doesn't. Please refer to
 // http://unicode.org/reports/tr9/ for more information.
 base::i18n::TextDirection GetCharacterDirection(UChar32 character) {
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();

[msw, 2017/04/28 22:04:03]

This function is called heavily, cache the value (or at least the presence of a
value, so the typical production codepath isn't hit with commandline checks for
each call), maybe:

namespace {

bool HasForcedTextDirection() {
  static bool value =
base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kForceTextDirection);
  return value;  
}

}  // namespace

...

  if (HasForcedTextDirection()) {
    std::string force_flag = ...
  }

[Kevin Bailey, 2017/04/29 04:24:03]

Done.

+  if (command_line->HasSwitch(switches::kForceTextDirection)) {
+    std::string force_flag =
+        command_line->GetSwitchValueASCII(switches::kForceTextDirection);
+
+    if (force_flag == switches::kForceUIDirectionRTL)
+      return base::i18n::RIGHT_TO_LEFT;
+    if (force_flag == switches::kForceUIDirectionLTR)
+      return base::i18n::LEFT_TO_RIGHT;
+  }
   // Now that we have the character, we use ICU in order to query for the
   // appropriate Unicode BiDi character type.
   int32_t property = u_getIntPropertyValue(character, UCHAR_BIDI_CLASS);