Bug 1243720 - Send accessibility theme state down to the content process on Windows. r=jimm

--HG--
extra : commitid : Bl9KE70LQHT
extra : rebase_source : 001c5608ccc5024d7000d26fcd35e247b62925f4
extra : amend_source : 22a5a6bd72dc54bfb16b159237d94375862abecc

widget/windows/nsLookAndFeel.cpp

@@ -65,7 +65,9 @@ static int32_t GetSystemParam(long flag, int32_t def)
     return ::SystemParametersInfo(flag, 0, &value, 0) ? value : def;
 }
 
-nsLookAndFeel::nsLookAndFeel() : nsXPLookAndFeel()
+nsLookAndFeel::nsLookAndFeel()
+  : nsXPLookAndFeel()
+  , mUseAccessibilityTheme(0)
 {
   mozilla::Telemetry::Accumulate(mozilla::Telemetry::TOUCH_ENABLED_DEVICE,
                                  WinUtils::IsTouchDeviceSupportPresent());
@@ -359,7 +361,16 @@ nsLookAndFeel::GetIntImpl(IntID aID, int32_t &aResult)
         // High contrast is a misnomer under Win32 -- any theme can be used with it,
         // e.g. normal contrast with large fonts, low contrast, etc.
         // The high contrast flag really means -- use this theme and don't override it.
-        aResult = nsUXThemeData::IsHighContrastOn();
+        if (XRE_IsContentProcess()) {
+          // If we're running in the content process, then the parent should
+          // have sent us the accessibility state when nsLookAndFeel
+          // initialized, and stashed it in the mUseAccessibilityTheme cache.
+          aResult = mUseAccessibilityTheme;
+        } else {
+          // Otherwise, we can ask the OS to see if we're using High Contrast
+          // mode.
+          aResult = nsUXThemeData::IsHighContrastOn();
+        }
         break;
     case eIntID_ScrollArrowStyle:
         aResult = eScrollArrowStyle_Single;
@@ -663,3 +674,29 @@ nsLookAndFeel::GetPasswordCharacterImpl()
 #define UNICODE_BLACK_CIRCLE_CHAR 0x25cf
   return UNICODE_BLACK_CIRCLE_CHAR;
 }
+
+nsTArray<LookAndFeelInt>
+nsLookAndFeel::GetIntCacheImpl()
+{
+  nsTArray<LookAndFeelInt> lookAndFeelIntCache =
+    nsXPLookAndFeel::GetIntCacheImpl();
+
+  LookAndFeelInt useAccessibilityTheme;
+  useAccessibilityTheme.id = eIntID_UseAccessibilityTheme;
+  useAccessibilityTheme.value = GetInt(eIntID_UseAccessibilityTheme);
+  lookAndFeelIntCache.AppendElement(useAccessibilityTheme);
+
+  return lookAndFeelIntCache;
+}
+
+void
+nsLookAndFeel::SetIntCacheImpl(const nsTArray<LookAndFeelInt>& aLookAndFeelIntCache)
+{
+  for (auto entry : aLookAndFeelIntCache) {
+    if (entry.id == eIntID_UseAccessibilityTheme) {
+      mUseAccessibilityTheme = entry.value;
+      break;
+    }
+  }
+}
+

widget/windows/nsLookAndFeel.h

@@ -54,6 +54,12 @@ public:
                            gfxFontStyle& aFontStyle,
                            float aDevPixPerCSSPixel);
   virtual char16_t GetPasswordCharacterImpl();
+
+  virtual nsTArray<LookAndFeelInt> GetIntCacheImpl();
+  virtual void SetIntCacheImpl(const nsTArray<LookAndFeelInt>& aLookAndFeelIntCache);
+
+private:
+  int32_t mUseAccessibilityTheme;
 };
 
 #endif