Backout Bug 930793 - Remove favor performance mode (we have still racy b2g tests), a=backout

docshell/base/nsDocShell.cpp

@@ -211,6 +211,9 @@ static bool gAddedPreferencesVarCache = false;
 
 bool nsDocShell::sUseErrorPages = false;
 
+// Number of documents currently loading
+static int32_t gNumberOfDocumentsLoading = 0;
+
 // Global count of existing docshells.
 static int32_t gDocShellCount = 0;
 
@@ -241,6 +244,17 @@ static PRLogModuleInfo* gDocShellLeakLog;
 const char kBrandBundleURL[]      = "chrome://branding/locale/brand.properties";
 const char kAppstringsBundleURL[] = "chrome://global/locale/appstrings.properties";
 
+static void
+FavorPerformanceHint(bool perfOverStarvation)
+{
+    nsCOMPtr<nsIAppShell> appShell = do_GetService(kAppShellCID);
+    if (appShell) {
+        appShell->FavorPerformanceHint(perfOverStarvation,
+                                       Preferences::GetUint("docshell.event_starvation_delay_hint",
+                                                            NS_EVENT_STARVATION_DELAY_HINT));
+    }
+}
+
 //*****************************************************************************
 // <a ping> support
 //*****************************************************************************
@@ -6852,6 +6866,14 @@ nsDocShell::EndPageLoad(nsIWebProgress * aProgress,
         mIsExecutingOnLoadHandler = false;
 
         mEODForCurrentDocument = true;
+
+        // If all documents have completed their loading
+        // favor native event dispatch priorities
+        // over performance
+        if (--gNumberOfDocumentsLoading == 0) {
+          // Hint to use normal native event dispatch priorities 
+          FavorPerformanceHint(false);
+        }
     }
     /* Check if the httpChannel has any cache-control related response headers,
      * like no-store, no-cache. If so, update SHEntry so that 
@@ -7855,6 +7877,12 @@ nsDocShell::RestoreFromHistory()
     mSavingOldViewer = false;
     mEODForCurrentDocument = false;
 
+    // Tell the event loop to favor plevents over user events, see comments
+    // in CreateContentViewer.
+    if (++gNumberOfDocumentsLoading == 1)
+        FavorPerformanceHint(true);
+
+
     if (oldMUDV && newMUDV) {
         newMUDV->SetMinFontSize(minFontSize);
         newMUDV->SetTextZoom(textZoom);
@@ -8251,6 +8279,16 @@ nsDocShell::CreateContentViewer(const char *aContentType,
       }
     }
 
+    // Give hint to native plevent dispatch mechanism. If a document
+    // is loading the native plevent dispatch mechanism should favor
+    // performance over normal native event dispatch priorities.
+    if (++gNumberOfDocumentsLoading == 1) {
+      // Hint to favor performance for the plevent notification mechanism.
+      // We want the pages to load as fast as possible even if its means 
+      // native messages might be starved.
+      FavorPerformanceHint(true);
+    }
+
     if (onLocationChangeNeeded) {
       FireOnLocationChange(this, request, mCurrentURI, 0);
     }