Changes to content/ to facilitate new zoom extension API

content/public/common/page_zoom.h

Index: content/public/common/page_zoom.h
diff --git a/content/public/common/page_zoom.h b/content/public/common/page_zoom.h
index aa5e56a90711b089987afdbcf17eafd49ddf67e2..f831bf530a6a034128dbb90a4c5dce0689664826 100644
--- a/content/public/common/page_zoom.h
+++ b/content/public/common/page_zoom.h
@@ -5,6 +5,10 @@
 #ifndef CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_
 #define CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_
 
+#include <string>
+
+#include "base/logging.h"
+#include "base/values.h"
 #include "content/common/content_export.h"
 
 namespace content {
@@ -39,6 +43,34 @@ CONTENT_EXPORT bool ZoomValuesEqual(double value_a, double value_b);
 CONTENT_EXPORT double ZoomLevelToZoomFactor(double zoom_level);
 CONTENT_EXPORT double ZoomFactorToZoomLevel(double factor);
 
+// Defines how zoom changes are handled.
+// |kZoomModeDefault| results in default zoom behavior, i.e. zoom changes are
+//     handled automatically and on a per-origin basis, meaning that other
+//     tabs navigated to the same origin will also zoom.
+// |kZoomModeIsolated| results in zoom changes being handled automatically,
+//     but on a per-tab basis. Tabs in this zoom mode will not be affected by
+//     zoom changes in other tabs, and vice versa.
+// |kZoomModeManual| overrides the automatic handling of zoom changes. The
+//     |onZoomChange| event will still be dispatched, but the page will not
+//     actually be zoomed. These zoom changes can be handled manually by
+//     listening for the |onZoomChange| event. Zooming in this mode is also on
+//     a per-tab basis.
+// |kZoomModeDisabled| disables all zooming in this tab. The tab will revert
+//     to default (100%) zoom, and all attempted zoom changes will be ignored.
+enum ZoomMode {
+  kZoomModeDefault,
+  kZoomModeIsolated,
+  kZoomModeManual,
+  kZoomModeDisabled,
+};
+
+// Details for the |onZoomChange| event.
+struct ZoomChangeDetails {
+  double old_zoom_level;
+  double new_zoom_level;
+  content::ZoomMode zoom_mode;
+};
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_PAGE_ZOOM_H_