Handle long press in PDF documents.

chrome/browser/resources/pdf/pdf.js

Index: chrome/browser/resources/pdf/pdf.js
diff --git a/chrome/browser/resources/pdf/pdf.js b/chrome/browser/resources/pdf/pdf.js
index da5793d9b0dd2e09d771c67cb3c493645f3625ad..993f7b3aeaca9aa982d2baa2cdb2bfd256f0ed0a 100644
--- a/chrome/browser/resources/pdf/pdf.js
+++ b/chrome/browser/resources/pdf/pdf.js
@@ -245,6 +245,8 @@ function PDFViewer(browserApi) {
   document.addEventListener('keydown', this.handleKeyEvent_.bind(this));
   document.addEventListener('mousemove', this.handleMouseEvent_.bind(this));
   document.addEventListener('mouseout', this.handleMouseEvent_.bind(this));
+  document.addEventListener('contextmenu',
+      this.handleContextMenuEvent_.bind(this));
 
   var tabId = this.browserApi_.getStreamInfo().tabId;
   this.navigator_ = new Navigator(
@@ -410,6 +412,17 @@ PDFViewer.prototype = {
       this.toolbarManager_.hideToolbarsForMouseOut();
   },
 
+  handleContextMenuEvent_: function(e) {
+    // Stop Chrome from popping up the context menu on long press. We need to
+    // make sure the start event did not have 2 touches because we don't want
+    // to block two finger tap opening the context menu. We check for
+    // firesTouchEvents in order to not block the context menu on right click.
+    if (e.sourceCapabilities.firesTouchEvents &&
+        !this.gestureDetector_.wasTwoFingerTouch()) {
+      e.preventDefault();
+    }
+  },
+
   /**
    * @private
    * Rotate the plugin clockwise.