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

Fixed layout mode can now be enabled with the command line
flag --enable-fixed-layout.

This mode does not interact well with zoom at this point in time. This will be fixed shortly.

This bug replaces http://codereview.chromium.org/7764006/ which is no longer relevant. 

BUG=none
TEST=manually


Review URL: http://codereview.chromium.org/7831028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@123126 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 39 insertions, 0 deletions

diff --git a/build/common.gypi b/build/common.gypi
index 056d797..fa82663 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -42,6 +42,9 @@
           # Disable Virtual keyboard support by default.
           'use_virtual_keyboard%': 0,
 
+          # Disable viewport meta tag by default.
+          'enable_viewport%': 0,
+
           # Default setting for use_skia on mac platform.
           # This is typically overridden in use_skia_on_mac.gypi.
           'use_skia_on_mac%': 0,
@@ -53,6 +56,7 @@
         'use_ash%': '<(use_ash)',
         'use_openssl%': '<(use_openssl)',
         'use_virtual_keyboard%': '<(use_virtual_keyboard)',
+        'enable_viewport%': '<(enable_viewport)',
         'use_skia_on_mac%': '<(use_skia_on_mac)',
 
         # Compute the architecture that we're building on.
@@ -95,6 +99,7 @@
       'use_ash%': '<(use_ash)',
       'use_openssl%': '<(use_openssl)',
       'use_virtual_keyboard%': '<(use_virtual_keyboard)',
+      'enable_viewport%': '<(enable_viewport)',
       'use_skia_on_mac%': '<(use_skia_on_mac)',
 
       # We used to provide a variable for changing how libraries were built.
@@ -426,6 +431,7 @@
     'chromeos%': '<(chromeos)',
     'chromeos_gtk%': '<(chromeos_gtk)',
     'use_virtual_keyboard%': '<(use_virtual_keyboard)',
+    'enable_viewport%': '<(enable_viewport)',
     'use_skia_on_mac%': '<(use_skia_on_mac)',
     'use_xi2_mt%':'<(use_xi2_mt)',
     'file_manager_extension%': '<(file_manager_extension)',
@@ -1110,6 +1116,9 @@
       ['enable_pepper_threading==1', {
         'defines': ['ENABLE_PEPPER_THREADING'],
       }],
+      ['enable_viewport==1', {
+        'defines': ['ENABLE_VIEWPORT'],
+      }],
       ['configuration_policy==1', {
         'defines': ['ENABLE_CONFIGURATION_POLICY'],
       }],
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index ccd1ece..34901fe 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -637,6 +637,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kAuditAllHandles,
     switches::kAuditHandles,
     switches::kChromeFrame,
+    switches::kDefaultDeviceScaleFactor,
     switches::kDisable3DAPIs,
     switches::kDisableAcceleratedCompositing,
     switches::kDisableApplicationCache,
@@ -667,6 +668,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kDomAutomationController,
     switches::kEnableAccessibilityLogging,
     switches::kEnableDCHECK,
+    switches::kEnableFixedLayout,
     switches::kEnableGamepad,
     switches::kEnableGPUServiceLogging,
     switches::kEnableGPUClientLogging,
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 8ff2a0b..4d55177 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1096,4 +1096,6 @@ void content::RenderWidgetHostViewPort::GetDefaultScreenInfo(
   // TODO(derat): Don't hardcode this?
   results->depth = 24;
   results->depthPerComponent = 8;
+  results->verticalDPI = 96;
+  results->horizontalDPI = 96;
 }
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 7c7849b..51879ef 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -36,6 +36,10 @@ const char kBrowserSubprocessPath[]         = "browser-subprocess-path";
 // as a dependent process of the Chrome Frame plugin.
 const char kChromeFrame[]                   = "chrome-frame";
 
+// The default device scale factor to apply to contents in the absence of
+// a viewport meta tag.
+const char kDefaultDeviceScaleFactor[]      = "default-device-scale-factor";
+
 // Disables client-visible 3D APIs, in particular WebGL and Pepper 3D.
 // This is controlled by policy and is kept separate from the other
 // enable/disable switches to avoid accidentally regressing the policy
@@ -235,6 +239,10 @@ const char kEnableDeviceMotion[]            = "enable-device-motion";
 // Enables the fastback page cache.
 const char kEnableFastback[]                = "enable-fastback";
 
+// By default, a page is laid out to fill the entire width of the window.
+// This flag fixes the layout of the page to a default of 980 CSS pixels.
+const char kEnableFixedLayout[]             = "enable-fixed-layout";
+
 // Enable the JavaScript Full Screen API.
 const char kDisableFullScreen[]             = "disable-fullscreen";
 
diff --git a/content/public/common/content_switches.h b/content/public/common/content_switches.h
index 5b4a624..106a716 100644
--- a/content/public/common/content_switches.h
+++ b/content/public/common/content_switches.h
@@ -23,6 +23,7 @@ CONTENT_EXPORT extern const char kBrowserCrashTest[];
 CONTENT_EXPORT extern const char kBrowserSubprocessPath[];
 // TODO(jam): this doesn't belong in content.
 CONTENT_EXPORT extern const char kChromeFrame[];
+CONTENT_EXPORT extern const char kDefaultDeviceScaleFactor[];
 CONTENT_EXPORT extern const char kDisable3DAPIs[];
 CONTENT_EXPORT extern const char kDisableAccelerated2dCanvas[];
 CONTENT_EXPORT extern const char kDisableAcceleratedCompositing[];
@@ -82,6 +83,7 @@ CONTENT_EXPORT extern const char kEnableDeferred2dCanvas[];
 extern const char kEnableCompositeToTexture[];
 CONTENT_EXPORT extern const char kEnableDeviceMotion[];
 extern const char kEnableFastback[];
+CONTENT_EXPORT extern const char kEnableFixedLayout[];
 CONTENT_EXPORT extern const char kDisableFullScreen[];
 extern const char kEnablePointerLock[];
 extern const char kEnableGamepad[];
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 5c73dfc..74af1c5 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -20,6 +20,7 @@
 #include "base/path_service.h"
 #include "base/process_util.h"
 #include "base/string_piece.h"
+#include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
@@ -527,6 +528,15 @@ RenderViewImpl::RenderViewImpl(
   if (command_line.HasSwitch(switches::kDomAutomationController))
     enabled_bindings_ |= content::BINDINGS_POLICY_DOM_AUTOMATION;
 
+  bool enable_fixed_layout =
+      command_line.HasSwitch(switches::kEnableFixedLayout);
+  webview()->enableFixedLayoutMode(enable_fixed_layout);
+  if (enable_fixed_layout)
+      webview()->settings()->setFixedElementsLayoutRelativeToFrame(true);
+  base::StringToInt(command_line.GetSwitchValueASCII(
+                        switches::kDefaultDeviceScaleFactor),
+                    &default_device_scale_factor_);
+
   content::GetContentClient()->renderer()->RenderViewCreated(this);
 }
 
@@ -4382,6 +4392,10 @@ void RenderViewImpl::OnResize(const gfx::Size& new_size,
                               const gfx::Rect& resizer_rect,
                               bool is_fullscreen) {
   if (webview()) {
+    // This setting has no effect if fixed layout is not enabled.
+    if (default_device_scale_factor_)
+      webview()->settings()->setLayoutFallbackWidth(
+          new_size.width() / default_device_scale_factor_);
     webview()->hidePopups();
     if (send_preferred_size_changes_) {
       webview()->mainFrame()->setCanHaveScrollbars(
diff --git a/content/renderer/render_view_impl.h b/content/renderer/render_view_impl.h
index 4e98228..c79204c 100644
--- a/content/renderer/render_view_impl.h
+++ b/content/renderer/render_view_impl.h
@@ -1015,6 +1015,8 @@ class RenderViewImpl : public RenderWidget,
   // should be drawn.
   gfx::Size disable_scrollbars_size_limit_;
 
+  int default_device_scale_factor_;
+
   // Loading state -------------------------------------------------------------
 
   // True if the top level frame is currently being loaded.