PDF: Add shortcut to toggle fit-to-{page,width}.

chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js

Index: chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js
diff --git a/chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js b/chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js
index 060178fcc6fe214d82b0b5d3ffdf5957b50346e7..71a72d6d3b9648aac8b91b499d023839f7e4c198 100644
--- a/chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js
+++ b/chrome/browser/resources/pdf/elements/viewer-zoom-toolbar/viewer-zoom-toolbar.js
@@ -38,6 +38,21 @@
       this.$['zoom-out-button'].tooltips = [this.strings.tooltipZoomOut];
     },
 
+    /**
+     * Toggle the state of the fit-button when something external, e.g. the
+     * fit-button equivalent shortcut key, toggles the zoom state.
+     */
+    toggleFitButtonUIState: function() {
+      var button = this.$['fit-button'];
+      if (button.activeIndex == FIT_TO_WIDTH)
+        button.activeIndex = FIT_TO_PAGE;
+      else
+        button.activeIndex = FIT_TO_WIDTH;
+    },
+
+    /**
+     * Handle clicks of the fit-button.
+     */
     fitToggle: function() {
       if (this.$['fit-button'].activeIndex == FIT_TO_WIDTH)
         this.fire('fit-to-width');
@@ -45,10 +60,16 @@
         this.fire('fit-to-page');
     },
 
+    /**
+     * Handle clicks of the zoom-in-button.
+     */
     zoomIn: function() {
       this.fire('zoom-in');
     },
 
+    /**
+     * Handle clicks of the zoom-out-button.
+     */
     zoomOut: function() {
       this.fire('zoom-out');
     },