Add a minimum offset for the OOP PDF toolbar

On platforms which have an overlay scrollbar (namely Mac) the toolbar in OOP PDF appears to be too low to the bottom and right of the screen. This adds a minimum offset for the toolbar.

BUG=303491

Review URL: https://codereview.chromium.org/293613002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272367 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/pdf/pdf.js

@@ -24,6 +24,12 @@ function getScrollbarWidth() {
   return result;
 }
 
+/**
+ * The minimum number of pixels to offset the toolbar by from the bottom and
+ * right side of the screen.
+ */
+PDFViewer.MIN_TOOLBAR_OFFSET = 15;
+
 /**
  * Creates a new PDFViewer. There should only be one of these objects per
  * document.
@@ -325,8 +331,12 @@ PDFViewer.prototype = {
     var hasScrollbars = this.viewport_.documentHasScrollbars();
     var scrollbarWidth = this.viewport_.scrollbarWidth;
     // Offset the toolbar position so that it doesn't move if scrollbars appear.
-    var toolbarRight = hasScrollbars.vertical ? 0 : scrollbarWidth;
-    var toolbarBottom = hasScrollbars.horizontal ? 0 : scrollbarWidth;
+    var toolbarRight = Math.max(PDFViewer.MIN_TOOLBAR_OFFSET, scrollbarWidth);
+    var toolbarBottom = Math.max(PDFViewer.MIN_TOOLBAR_OFFSET, scrollbarWidth);
+    if (hasScrollbars.vertical)
+      toolbarRight -= scrollbarWidth;
+    if (hasScrollbars.horizontal)
+      toolbarBottom -= scrollbarWidth;
     this.toolbar_.style.right = toolbarRight + 'px';
     this.toolbar_.style.bottom = toolbarBottom + 'px';