Bug 518805 - Don't do meta refreshes when backgrounded r=bz

This is controlled by browser.meta_refresh_when_inactive.disabled, which
is false (allow refreshes) on desktop, and true (disable refreshes) on Fennec

docshell/base/nsDocShell.cpp

@@ -780,6 +780,7 @@ nsDocShell::nsDocShell()
   , mAllowKeywordFixup(false)
   , mIsOffScreenBrowser(false)
   , mIsActive(true)
+  , mDisableMetaRefreshWhenInactive(false)
   , mIsPrerendered(false)
   , mIsAppTab(false)
   , mUseGlobalHistory(false)
@@ -5630,6 +5631,10 @@ nsDocShell::Create()
     gAddedPreferencesVarCache = true;
   }
 
+  mDisableMetaRefreshWhenInactive =
+    Preferences::GetBool("browser.meta_refresh_when_inactive.disabled",
+                         mDisableMetaRefreshWhenInactive);
+
   mDeviceSizeIsPageSize =
     Preferences::GetBool("docshell.device_size_is_page_size",
                          mDeviceSizeIsPageSize);
@@ -6132,6 +6137,15 @@ nsDocShell::SetIsActiveInternal(bool aIsActive, bool aIsHidden)
     }
   }
 
+  // Restart or stop meta refresh timers if necessary
+  if (mDisableMetaRefreshWhenInactive) {
+    if (mIsActive) {
+      ResumeRefreshURIs();
+    } else {
+      SuspendRefreshURIs();
+    }
+  }
+
   return NS_OK;
 }
 
@@ -6593,10 +6607,9 @@ nsDocShell::RefreshURI(nsIURI* aURI, int32_t aDelay, bool aRepeat,
                       NS_ERROR_FAILURE);
   }
 
-  if (busyFlags & BUSY_FLAGS_BUSY) {
-    // We are busy loading another page. Don't create the
-    // timer right now. Instead queue up the request and trigger the
-    // timer in EndPageLoad().
+  if (busyFlags & BUSY_FLAGS_BUSY || (!mIsActive && mDisableMetaRefreshWhenInactive)) {
+    // We don't  want to create the timer right now. Instead queue up the request
+    // and trigger the timer in EndPageLoad() or whenever we become active.
     mRefreshURIList->AppendElement(refreshTimer);
   } else {
     // There is no page loading going on right now.  Create the
@@ -7549,7 +7562,8 @@ nsDocShell::EndPageLoad(nsIWebProgress* aProgress,
   }
   // if there's a refresh header in the channel, this method
   // will set it up for us.
-  RefreshURIFromQueue();
+  if (mIsActive || !mDisableMetaRefreshWhenInactive)
+    RefreshURIFromQueue();
 
   // Test whether this is the top frame or a subframe
   bool isTopFrame = true;