bug 39570; we were using the Western font to determine the height of the

URL bar, and this caused the Japanese text to be truncated; we now use the
locale's language group when the caller does not pass us the correct one;
r=nhotta

gfx/public/nsDeviceContext.h

@@ -100,13 +100,14 @@ protected:
   nsresult AliasFont(const nsString& aFont, 
                      const nsString& aAlias, const nsString& aAltAlias,
                      PRBool aForceAlias);
+  void GetLocaleLangGroup(void);
 
   float             mTwipsToPixels;
   float             mPixelsToTwips;
   float             mAppUnitsToDevUnits;
   float             mDevUnitsToAppUnits;
   nsFontCache       *mFontCache;
-  nsCOMPtr<nsIAtom> mWestern; // XXX temporary fix for performance bug - erik
+  nsCOMPtr<nsIAtom> mLocaleLangGroup; // XXX temp fix for performance bug - erik
   float             mZoom;
   float             mTextZoom;
   float             mGammaValue;

gfx/src/nsDeviceContext.cpp

@@ -37,6 +37,8 @@
 #include "nsVoidArray.h"
 #include "nsIFontMetrics.h"
 #include "nsHashtable.h"
+#include "nsILanguageAtomService.h"
+#include "nsIServiceManager.h"
 
 class nsFontCache
 {
@@ -236,6 +238,21 @@ nsresult DeviceContextImpl::CreateFontCache()
   return NS_OK;
 }
 
+void
+DeviceContextImpl::GetLocaleLangGroup(void)
+{
+  if (!mLocaleLangGroup) {
+    nsCOMPtr<nsILanguageAtomService> langService;
+    langService = do_GetService(NS_LANGUAGEATOMSERVICE_PROGID);
+    if (langService) {
+      langService->GetLocaleLanguageGroup(getter_AddRefs(mLocaleLangGroup));
+    }
+    if (!mLocaleLangGroup) {
+      mLocaleLangGroup = getter_AddRefs(NS_NewAtom("x-western"));
+    }
+  }
+}
+
 NS_IMETHODIMP DeviceContextImpl::GetMetricsFor(const nsFont& aFont,
   nsIAtom* aLangGroup, nsIFontMetrics*& aMetrics)
 {
@@ -246,12 +263,12 @@ NS_IMETHODIMP DeviceContextImpl::GetMetricsFor(const nsFont& aFont,
       return rv;
     }
     // XXX temporary fix for performance problem -- erik
-    mWestern = getter_AddRefs(NS_NewAtom("x-western"));
+    GetLocaleLangGroup();
   }
 
   // XXX figure out why aLangGroup is NULL sometimes
   if (!aLangGroup) {
-    aLangGroup = mWestern;
+    aLangGroup = mLocaleLangGroup;
   }
 
   return mFontCache->GetMetricsFor(aFont, aLangGroup, aMetrics);
@@ -266,9 +283,9 @@ NS_IMETHODIMP DeviceContextImpl::GetMetricsFor(const nsFont& aFont, nsIFontMetri
       return rv;
     }
     // XXX temporary fix for performance problem -- erik
-    mWestern = getter_AddRefs(NS_NewAtom("x-western"));
+    GetLocaleLangGroup();
   }
-  return mFontCache->GetMetricsFor(aFont, mWestern, aMetrics);
+  return mFontCache->GetMetricsFor(aFont, mLocaleLangGroup, aMetrics);
 }
 
 NS_IMETHODIMP DeviceContextImpl :: SetZoom(float aZoom)

gfx/src/ps/nsDeviceContextPS.cpp

@@ -369,8 +369,8 @@ NS_IMETHODIMP nsDeviceContextPS :: ConvertPixel(nscolor aColor, PRUint32 & aPixe
  */
 NS_IMETHODIMP nsDeviceContextPS::GetMetricsFor(const nsFont& aFont, nsIFontMetrics  *&aMetrics)
 {
-    mWestern = getter_AddRefs(NS_NewAtom("x-western"));
-    return GetMetricsFor(aFont, mWestern, aMetrics);
+    GetLocaleLangGroup();
+    return GetMetricsFor(aFont, mLocaleLangGroup, aMetrics);
 }
 
 NS_IMETHODIMP nsDeviceContextPS::GetMetricsFor(const nsFont& aFont, nsIAtom* aLangGroup, nsIFontMetrics  *&aMetrics)