Compute pageScaleFactor on page so that fixed layout page fits width of window.

chrome/renderer/chrome_render_view_observer.cc

Index: chrome/renderer/chrome_render_view_observer.cc
diff --git a/chrome/renderer/chrome_render_view_observer.cc b/chrome/renderer/chrome_render_view_observer.cc
index 935c6e9e8089d8bab27f8ab23a14f9c9a325c3cd..dbbb0f0ee1068b66cbb3a677cd2e294cffa568e2 100644
--- a/chrome/renderer/chrome_render_view_observer.cc
+++ b/chrome/renderer/chrome_render_view_observer.cc
@@ -22,6 +22,7 @@
 #include "chrome/renderer/chrome_render_process_observer.h"
 #include "chrome/renderer/content_settings_observer.h"
 #include "chrome/renderer/extensions/extension_dispatcher.h"
+#include "chrome/renderer/extensions/extension_helper.h"
 #include "chrome/renderer/external_host_bindings.h"
 #include "chrome/renderer/frame_sniffer.h"
 #include "chrome/renderer/prerender/prerender_helper.h"
@@ -29,6 +30,7 @@
 #include "chrome/renderer/translate_helper.h"
 #include "chrome/renderer/webview_color_overlay.h"
 #include "content/public/common/bindings_policy.h"
+#include "content/public/common/view_type.h"
 #include "content/public/renderer/render_view.h"
 #include "content/public/renderer/content_renderer_client.h"
 #include "net/base/data_url.h"
@@ -93,6 +95,10 @@ static const size_t kMaxIndexChars = 65535;
 static const int kThumbnailWidth = 212;
 static const int kThumbnailHeight = 132;
 
+// The default layout width for pages when fixed layout is enabled.
+static const int kDefaultLayoutWidth = 980;
+static const int kDefaultLayoutHeight = 640;
+
 // Constants for UMA statistic collection.
 static const char kWWWDotGoogleDotCom[] = "www.google.com";
 static const char kMailDotGoogleDotCom[] = "mail.google.com";
@@ -372,6 +378,27 @@ void ChromeRenderViewObserver::OnSetAsInterstitial() {
 }
 
 void ChromeRenderViewObserver::Navigate(const GURL& url) {
+  ExtensionHelper* extension_helper = ExtensionHelper::Get(render_view());
+  bool is_tab_contents = extension_helper &&
+      extension_helper->view_type() == content::VIEW_TYPE_TAB_CONTENTS;
+  const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  // Only use fixed layout on tab contents.
+  if (is_tab_contents && cmd_line->HasSwitch(switches::kEnableFixedLayout)) {
+    WebSize viewSize = render_view()->GetWebView()->size();
+    int layoutHeight =
+        viewSize.height ?
+            viewSize.height * kDefaultLayoutWidth / viewSize.width :
+            kDefaultLayoutHeight;
+    WebSize layout_size(kDefaultLayoutWidth, layoutHeight);
+    render_view()->GetWebView()->enableFixedLayoutMode(true);
+    render_view()->GetWebView()->setFixedLayoutSize(layout_size);
+    render_view()->GetWebView()->
+        setShouldLayoutFixedElementsRelativeToFrame(true);
+  } else {
+    render_view()->GetWebView()->enableFixedLayoutMode(false);
+    render_view()->GetWebView()->
+        setShouldLayoutFixedElementsRelativeToFrame(false);
+  }
   // Execute cache clear operations that were postponed until a navigation
   // event (including tab reload).
   if (chrome_render_process_observer_)