Bug 680077 - Use Util.isTablet() everywhere to check if tablet mode is on (r=mbrubeck)

Use it instead of checking for a 'tablet' attribute in Elements.urlbarState
everywhere.

mobile/chrome/content/Util.js

@@ -161,15 +161,29 @@ let Util = {
     return (!appInfo || appInfo.getService(Ci.nsIXULRuntime).processType == Ci.nsIXULRuntime.PROCESS_TYPE_DEFAULT);
   },
 
-  isTablet: function isTablet() {
+  isTablet: function isTablet(options) {
+    let forceUpdate = options && 'forceUpdate' in options && options.forceUpdate;
+
+    if ('_isTablet' in this && !forceUpdate)
+      return this._isTablet;
+
+    let tabletPref = Services.prefs.getIntPref("browser.ui.layout.tablet");
+
+    // Act according to user prefs if tablet mode has been
+    // explicitly disabled or enabled.
+    if (tabletPref == 0)
+      return this._isTablet = false;
+    else if (tabletPref == 1)
+      return this._isTablet = true;
+
     let dpi = this.displayDPI;
     if (dpi <= 96)
-      return (window.innerWidth > 1024);
+      return this._isTablet = (window.innerWidth > 1024);
 
     // See the tablet_panel_minwidth from mobile/themes/core/defines.inc
     let tablet_panel_minwidth = 124;
     let dpmm = 25.4 * window.innerWidth / dpi;
-    return (dpmm >= tablet_panel_minwidth);
+    return this._isTablet = (dpmm >= tablet_panel_minwidth);
   },
 
   isPortrait: function isPortrait() {

mobile/chrome/content/browser-ui.js

@@ -186,7 +186,7 @@ var BrowserUI = {
   },
 
   lockToolbar: function lockToolbar() {
-    if (Elements.urlbarState.getAttribute("tablet"))
+    if (Util.isTablet())
       return;
     this._toolbarLocked++;
     document.getElementById("toolbar-moveable-container").top = "0";
@@ -549,8 +549,7 @@ var BrowserUI = {
   },
 
   updateTabletLayout: function updateTabletLayout() {
-    let tabletPref = Services.prefs.getIntPref("browser.ui.layout.tablet");
-    if (tabletPref == 1 || (tabletPref == -1 && Util.isTablet())) {
+    if (Util.isTablet({ forceUpdate: true })) {
       this.unlockToolbar();
       Elements.urlbarState.setAttribute("tablet", "true");
     } else {

mobile/chrome/content/browser.js

@@ -1038,7 +1038,7 @@ var Browser = {
   },
 
   tryFloatToolbar: function tryFloatToolbar(dx, dy) {
-    if (this.floatedWhileDragging || Elements.urlbarState.getAttribute("tablet"))
+    if (this.floatedWhileDragging || Util.isTablet())
       return;
 
     let [leftvis, ritevis, leftw, ritew] = Browser.computeSidebarVisibility(dx, dy);
@@ -1289,7 +1289,7 @@ Browser.MainDragger.prototype = {
     let bcr = browser.getBoundingClientRect();
     this._contentView = browser.getViewAt(clientX - bcr.left, clientY - bcr.top);
     this._stopAtSidebar = 0;
-    this._panToolbars = !Elements.urlbarState.getAttribute("tablet");
+    this._panToolbars = !Util.isTablet();
     if (this._sidebarTimeout) {
       clearTimeout(this._sidebarTimeout);
       this._sidebarTimeout = null;
@@ -1908,7 +1908,7 @@ const ContentTouchHandler = {
     // or if the urlbar is showing
     this.canCancelPan = (aX >= rect.left + kSafetyX) && (aX <= rect.right - kSafetyX) &&
                         (aY >= rect.top  + kSafetyY) &&
-                        (bcr.top == 0 || Elements.urlbarState.getAttribute("tablet"));
+                        (bcr.top == 0 || Util.isTablet());
   },
 
   tapDown: function tapDown(aX, aY) {
@@ -3155,7 +3155,7 @@ function rendererFactory(aBrowser, aCanvas) {
 var ViewableAreaObserver = {
   get width() {
     let width = this._width || window.innerWidth;
-    if (Elements.urlbarState.getAttribute("tablet")) {
+    if (Util.isTablet()) {
       let sidebarWidth = Math.round(Elements.tabs.getBoundingClientRect().width);
       width -= sidebarWidth;
     }
@@ -3164,7 +3164,7 @@ var ViewableAreaObserver = {
 
   get height() {
     let height = (this._height || window.innerHeight);
-    if (Elements.urlbarState.getAttribute("tablet"))
+    if (Util.isTablet())
       height -= BrowserUI.toolbarH;
     return height;
   },