Linux/CrOS smooth scrolling support - behind a flag.

Add runtime flag to control smooth scrolling. Add compile time flag handling for a GYP_DEFINE (enable_smooth_scrolling=1).

BUG=575,61140
TEST=compile still works without the flag. Compiling with the flag works once the WebKit change is landed, and then the flag appears in the about:flags page, and actually turns on that WebKit implementation.


Review URL: http://codereview.chromium.org/7034052

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@90136 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 37 insertions, 1 deletions

diff --git a/build/common.gypi b/build/common.gypi
index 65e6a65..8d70646 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -251,6 +251,9 @@
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'enable_register_protocol_handler%': '<(enable_register_protocol_handler)',
 
+    # Smooth scrolling is disabled by default.
+    'enable_smooth_scrolling%': 0,
+
     # The release channel that this build targets. This is used to restrict
     # channel-specific build options, like which installer packages to create.
     # The default is 'all', which does no channel-specific filtering.
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index f492ffd..64a3168 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -4323,6 +4323,12 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_PRELOAD_INSTANT_SEARCH_DESCRIPTION" desc="Description for the flag to preload Instant search">
         Preload the default search engine for Instant.
       </message>
+      <message name="IDS_FLAGS_ENABLE_SMOOTH_SCROLLING_NAME" desc="Title for the flag to turn on smooth scrolling">
+        Smooth Scrolling
+      </message>
+      <message name="IDS_FLAGS_ENABLE_SMOOTH_SCROLLING_DESCRIPTION" desc="Description for the flag to turn on smooth scrolling">
+        Enable the experimental smooth scrolling implementation.
+      </message>
       <message name="IDS_FLAGS_AUTO_LOGIN_NAME" desc="title for the flag to pre- and auto-login the user">
         Disable pre- and auto-login
       </message>
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index b5137f2..75f9d66 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -364,6 +364,18 @@ const Experiment kExperiments[] = {
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kEnableSyncTypedUrls)
   },
+  {
+    "enable-smooth-scrolling",  // FLAGS:RECORD_UMA
+    IDS_FLAGS_ENABLE_SMOOTH_SCROLLING_NAME,
+    IDS_FLAGS_ENABLE_SMOOTH_SCROLLING_DESCRIPTION,
+    // Can't expose the switch unless the code is compiled in.
+#if defined(ENABLE_SMOOTH_SCROLLING)
+    kOsAll,
+#else
+    0,
+#endif
+    SINGLE_VALUE_TYPE(switches::kEnableSmoothScrolling)
+  },
 };
 
 const Experiment* experiments = kExperiments;
diff --git a/chrome/browser/tab_contents/render_view_host_delegate_helper.cc b/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
index 9f6f388..0484959 100644
--- a/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
+++ b/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
@@ -341,6 +341,8 @@ WebPreferences RenderViewHostDelegateHelper::GetWebkitPrefs(
         prefs->GetBoolean(prefs::kWebKitAllowDisplayingInsecureContent);
     web_prefs.allow_running_insecure_content =
         prefs->GetBoolean(prefs::kWebKitAllowRunningInsecureContent);
+    web_prefs.enable_scroll_animator =
+        command_line.HasSwitch(switches::kEnableSmoothScrolling);
 
     // The user stylesheet watcher may not exist in a testing profile.
     if (profile->GetUserStyleSheetWatcher()) {
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index ad08b00..5c6cec9 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -4512,6 +4512,11 @@
             ['exclude', '^browser/ui/views/file_manager_dialog.h'],
           ]}
         ],
+        ['enable_smooth_scrolling==1', {
+          'defines': [
+            'ENABLE_SMOOTH_SCROLLING',
+          ],
+        }],
       ],
     },
     {
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index b1f74dd..b667a0f 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -479,6 +479,9 @@ const char kEnablePreconnect[]              = "enable-preconnect";
 // parameter to indicate if the provider should be the default.
 const char kEnableSearchProviderApiV2[]     = "enable-search-provider-api-v2";
 
+// On platforms that support it, enable smooth scroll animation.
+const char kEnableSmoothScrolling[]         = "enable-smooth-scrolling";
+
 // Enables TLS cached info extension.
 const char kEnableSSLCachedInfo[]  = "enable-ssl-cached-info";
 
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index c9f0db3..6770bd1 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -139,6 +139,7 @@ extern const char kEnablePreconnect[];
 extern const char kEnableRemoting[];
 extern const char kEnableResourceContentSettings[];
 extern const char kEnableSearchProviderApiV2[];
+extern const char kEnableSmoothScrolling[];
 extern const char kEnableSSLCachedInfo[];
 extern const char kEnableSync[];
 extern const char kEnableSyncAutofill[];
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index 57d7bd2..911cd87 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -327,6 +327,7 @@ IPC_STRUCT_TRAITS_BEGIN(WebPreferences)
   IPC_STRUCT_TRAITS_MEMBER(fullscreen_enabled)
   IPC_STRUCT_TRAITS_MEMBER(allow_displaying_insecure_content)
   IPC_STRUCT_TRAITS_MEMBER(allow_running_insecure_content)
+  IPC_STRUCT_TRAITS_MEMBER(enable_scroll_animator)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(WebMenuItem)
diff --git a/webkit/glue/webpreferences.cc b/webkit/glue/webpreferences.cc
index f55ec5f..362c212 100644
--- a/webkit/glue/webpreferences.cc
+++ b/webkit/glue/webpreferences.cc
@@ -81,7 +81,8 @@ WebPreferences::WebPreferences()
       fullscreen_enabled(false),
       allow_displaying_insecure_content(true),
       allow_running_insecure_content(false),
-      should_print_backgrounds(false) {
+      should_print_backgrounds(false),
+      enable_scroll_animator(false) {
 }
 
 WebPreferences::~WebPreferences() {
@@ -231,4 +232,5 @@ void WebPreferences::Apply(WebView* web_view) const {
   settings->setAllowDisplayOfInsecureContent(allow_displaying_insecure_content);
   settings->setAllowRunningOfInsecureContent(allow_running_insecure_content);
   settings->setShouldPrintBackgrounds(should_print_backgrounds);
+  settings->setEnableScrollAnimator(enable_scroll_animator);
 }
diff --git a/webkit/glue/webpreferences.h b/webkit/glue/webpreferences.h
index 5389cc4..78dc8f1 100644
--- a/webkit/glue/webpreferences.h
+++ b/webkit/glue/webpreferences.h
@@ -91,6 +91,7 @@ struct WebPreferences {
   bool allow_displaying_insecure_content;
   bool allow_running_insecure_content;
   bool should_print_backgrounds;
+  bool enable_scroll_animator;
 
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for