Bug 1235478 - Part 2: Don't update mMostRecentRefresh when nsRefreshDriver::ScheduleViewManagerFlush is called. r=mchang

--HG--
extra : transplant_source : %86e%80%9D%07%B0K%16%EB%FC%5D%9B%CA%D6%A1_%D2y%A0%7E

layout/base/nsRefreshDriver.cpp

@@ -1184,6 +1184,15 @@ nsRefreshDriver::EnsureTimerStarted(EnsureTimerStartedFlags aFlags)
     mActiveTimer->AddRefreshDriver(this);
   }
 
+  // When switching from an inactive timer to an active timer, the root
+  // refresh driver is skipped due to being set to the content refresh
+  // driver's timestamp. In case of EnsureTimerStarted is called from
+  // ScheduleViewManagerFlush, we should avoid this behavior to flush
+  // a paint in the same tick on the root refresh driver.
+  if (aFlags & eNeverAdjustTimer) {
+    return;
+  }
+
   // Since the different timers are sampled at different rates, when switching
   // timers, the most recent refresh of the new timer may be *before* the
   // most recent refresh of the old timer. However, the refresh driver time
@@ -2108,7 +2117,7 @@ nsRefreshDriver::ScheduleViewManagerFlush()
   NS_ASSERTION(mPresContext->IsRoot(),
                "Should only schedule view manager flush on root prescontexts");
   mViewManagerFlushIsPending = true;
-  EnsureTimerStarted();
+  EnsureTimerStarted(eNeverAdjustTimer);
 }
 
 void

layout/base/nsRefreshDriver.h

@@ -330,7 +330,8 @@ private:
   enum EnsureTimerStartedFlags {
     eNone = 0,
     eForceAdjustTimer = 1 << 0,
-    eAllowTimeToGoBackwards = 1 << 1
+    eAllowTimeToGoBackwards = 1 << 1,
+    eNeverAdjustTimer = 1 << 2,
   };
   void EnsureTimerStarted(EnsureTimerStartedFlags aFlags = eNone);
   void StopTimer();