Bug 1523692 - Set the prefers-reduce-motion value for test to the instance of nsLookAndFeel in child processes. r=snorp

So that we can query the test value in the child process properly.

Note that the APIs used for setting the prefers-reduced-motion value for testing
are only used on Android and MacOSX.  As for MacOSX we have a different
machinery (see bug 1486971) to deliver the test value without spinning native
event loop in the child process so the change here is valid only for Android.

Differential Revision: https://phabricator.services.mozilla.com/D18311

widget/PuppetWidget.cpp

@@ -28,6 +28,7 @@
 #include "nsIWidgetListener.h"
 #include "imgIContainer.h"
 #include "nsView.h"
+#include "nsXPLookAndFeel.h"
 #include "nsPrintfCString.h"
 
 using namespace mozilla;
@@ -903,10 +904,8 @@ struct CursorSurface {
   IntSize mSize;
 };
 
-void PuppetWidget::SetCursor(nsCursor aCursor,
-                             imgIContainer* aCursorImage,
-                             uint32_t aHotspotX,
-                             uint32_t aHotspotY) {
+void PuppetWidget::SetCursor(nsCursor aCursor, imgIContainer* aCursorImage,
+                             uint32_t aHotspotX, uint32_t aHotspotY) {
   if (!mTabChild) {
     return;
   }
@@ -945,7 +944,8 @@ void PuppetWidget::SetCursor(nsCursor aCursor,
 
   mCustomCursor = nullptr;
 
-  nsDependentCString cursorData(customCursorData ? customCursorData.get() : "", length);
+  nsDependentCString cursorData(customCursorData ? customCursorData.get() : "",
+                                length);
   if (!mTabChild->SendSetCursor(aCursor, hasCustomCursor, cursorData,
                                 customCursorSize.width, customCursorSize.height,
                                 stride, format, aHotspotX, aHotspotY, force)) {
@@ -1409,6 +1409,9 @@ nsresult PuppetWidget::SetPrefersReducedMotionOverrideForTest(bool aValue) {
     return NS_ERROR_FAILURE;
   }
 
+  nsXPLookAndFeel::GetInstance()->SetPrefersReducedMotionOverrideForTest(
+      aValue);
+
   mTabChild->SendSetPrefersReducedMotionOverrideForTest(aValue);
   return NS_OK;
 }
@@ -1418,6 +1421,7 @@ nsresult PuppetWidget::ResetPrefersReducedMotionOverrideForTest() {
     return NS_ERROR_FAILURE;
   }
 
+  nsXPLookAndFeel::GetInstance()->ResetPrefersReducedMotionOverrideForTest();
   mTabChild->SendResetPrefersReducedMotionOverrideForTest();
   return NS_OK;
 }