Bug 1002426 - Check resolution restore status via specialized flag. r=kats, r=tn

dom/base/nsDOMWindowUtils.cpp

@@ -577,7 +577,7 @@ nsDOMWindowUtils::GetResolution(float* aXResolution, float* aYResolution)
 }
 
 NS_IMETHODIMP
-nsDOMWindowUtils::GetIsHistoryRestored(bool* aIsHistoryRestored) {
+nsDOMWindowUtils::GetIsResolutionSet(bool* aIsResolutionSet) {
   if (!nsContentUtils::IsCallerChrome()) {
     return NS_ERROR_DOM_SECURITY_ERR;
   }
@@ -588,7 +588,7 @@ nsDOMWindowUtils::GetIsHistoryRestored(bool* aIsHistoryRestored) {
   }
 
   const nsIScrollableFrame* sf = presShell->GetRootScrollFrameAsScrollable();
-  *aIsHistoryRestored = sf && sf->DidHistoryRestore();
+  *aIsResolutionSet = sf && sf->IsResolutionSet();
 
   return NS_OK;
 }

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -48,7 +48,7 @@ interface nsIRunnable;
 interface nsICompositionStringSynthesizer;
 interface nsITranslationNodeList;
 
-[scriptable, uuid(8489681a-7407-457e-b889-53d1ae999b30)]
+[scriptable, uuid(aae2d993-366f-43e6-aa51-f2eb83935e7d)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -231,13 +231,13 @@ interface nsIDOMWindowUtils : nsISupports {
   void getResolution(out float aXResolution, out float aYResolution);
 
   /**
-   * Whether the current window has been restored from session history.
-   * This gives a way to check whether the provided resolution and scroll
-   * position are default values or restored from a previous session.
+   * Whether the resolution has been set by the user.
+   * This gives a way to check whether the provided resolution is the default
+   * value or restored from a previous session.
    *
    * Can only be accessed with chrome privileges.
    */
-  readonly attribute boolean isHistoryRestored;
+  readonly attribute boolean isResolutionSet;
 
   /**
    * Whether the next paint should be flagged as the first paint for a document.

layout/generic/nsGfxScrollFrame.cpp

@@ -1607,6 +1607,7 @@ ScrollFrameHelper::ScrollFrameHelper(nsContainerFrame* aOuter,
   , mCollapsedResizer(false)
   , mShouldBuildScrollableLayer(false)
   , mHasBeenScrolled(false)
+  , mIsResolutionSet(false)
 {
   mScrollingActive = IsAlwaysActive();
 
@@ -2795,6 +2796,7 @@ void
 ScrollFrameHelper::SetResolution(const gfxSize& aResolution)
 {
   mResolution = aResolution;
+  mIsResolutionSet = true;
 }
 
 static void
@@ -4538,6 +4540,7 @@ ScrollFrameHelper::RestoreState(nsPresState* aState)
   mDidHistoryRestore = true;
   mLastPos = mScrolledFrame ? GetLogicalScrollPosition() : nsPoint(0,0);
   mResolution = aState->GetResolution();
+  mIsResolutionSet = true;
 
   if (mIsRoot) {
     mOuter->PresContext()->PresShell()->SetResolution(mResolution.width, mResolution.height);

layout/generic/nsGfxScrollFrame.h

@@ -407,6 +407,10 @@ public:
   // True if this frame has been scrolled at least once
   bool mHasBeenScrolled:1;
 
+  // True if the frame's resolution has been set via SetResolution or restored
+  // via RestoreState.
+  bool mIsResolutionSet:1;
+
 protected:
   /**
    * @note This method might destroy the frame, pres shell and other objects.
@@ -658,6 +662,9 @@ public:
   virtual void ResetScrollPositionForLayerPixelAlignment() MOZ_OVERRIDE {
     mHelper.ResetScrollPositionForLayerPixelAlignment();
   }
+  virtual bool IsResolutionSet() const MOZ_OVERRIDE {
+    return mHelper.mIsResolutionSet;
+  }
   virtual bool DidHistoryRestore() const MOZ_OVERRIDE {
     return mHelper.mDidHistoryRestore;
   }
@@ -972,6 +979,9 @@ public:
   virtual void ResetScrollPositionForLayerPixelAlignment() MOZ_OVERRIDE {
     mHelper.ResetScrollPositionForLayerPixelAlignment();
   }
+  virtual bool IsResolutionSet() const MOZ_OVERRIDE {
+    return mHelper.mIsResolutionSet;
+  }
   virtual bool DidHistoryRestore() const MOZ_OVERRIDE {
     return mHelper.mDidHistoryRestore;
   }

layout/generic/nsIScrollableFrame.h

@@ -271,6 +271,10 @@ public:
    * Was the current presentation state for this frame restored from history?
    */
   virtual bool DidHistoryRestore() const = 0;
+  /**
+   * Was the current resolution set by the user or just default initialized?
+   */
+  virtual bool IsResolutionSet() const = 0;
   /**
    * Clear the flag so that DidHistoryRestore() returns false until the next
    * RestoreState call.

mobile/android/chrome/content/browser.js

@@ -4233,7 +4233,7 @@ Tab.prototype = {
   restoredSessionZoom: function() {
     let cwu = this.browser.contentWindow.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
 
-    if (this._restoreZoom && cwu.isHistoryRestored) {
+    if (this._restoreZoom && cwu.isResolutionSet) {
       return this._getGeckoZoom();
     }
     return null;