Bug 1026561 - The New Tab Page should be smarter about showing more tiles when on large screens [r=adw]

Bump up default columns to fit most Firefox users including 2560px wide resolutions.

browser/app/profile/firefox.js

@@ -1471,7 +1471,7 @@ pref("browser.newtabpage.enabled", true);
 pref("browser.newtabpage.rows", 3);
 
 // number of columns of newtab grid
-pref("browser.newtabpage.columns", 3);
+pref("browser.newtabpage.columns", 8);
 
 // directory tiles download URL
 pref("browser.newtabpage.directory.source", "chrome://global/content/directoryLinks.json");

browser/base/content/test/newtab/browser_newtab_bug752841.js

@@ -17,8 +17,8 @@ function runTests() {
   // Expected length of grid
   let expectedValues = [1, 1, 1, 1, 8, 10];
 
-   // Values before setting new pref values (9 is the default value -> 3 x 3)
-  let previousValues = [9, 1, 1, 1, 1, 8];
+   // Values before setting new pref values (24 is the default value -> 8 x 3)
+  let previousValues = [24, 1, 1, 1, 1, 8];
 
   let existingTab, existingTabGridLength, newTab, newTabGridLength;
   yield addNewTabPageTab();

browser/base/content/test/newtab/browser_newtab_drag_drop_ext.js

@@ -1,6 +1,8 @@
 /* Any copyright is dedicated to the Public Domain.
    http://creativecommons.org/publicdomain/zero/1.0/ */
 
+const PREF_NEWTAB_COLUMNS = "browser.newtabpage.columns";
+
 /*
  * These tests make sure that dragging and dropping sites works as expected.
  * Sites contained in the grid need to shift around to indicate the result
@@ -28,8 +30,11 @@ function runTests() {
   yield addNewTabPageTab();
   checkGrid("0,1,2,3,4,5,6,7p,8p");
 
+  // force the grid to be small enough that a pinned cell could be pushed out
+  Services.prefs.setIntPref(PREF_NEWTAB_COLUMNS, 3);
   yield simulateExternalDrop(7);
   checkGrid("0,1,2,3,4,5,7p,99p,8p");
+  Services.prefs.clearUserPref(PREF_NEWTAB_COLUMNS);
 
   // drag a new site beneath a pinned cell and make sure the pinned cell is
   // not moved
@@ -52,4 +57,4 @@ function runTests() {
 
   yield simulateExternalDrop(1);
   checkGrid("0p,99p,1p,2p,3,4,5,6,7");
-}
+}