Zoom Extension API (content changes)

content/common/view_messages.h

Index: content/common/view_messages.h
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index 4688fd6494f44ec7d8067b56b4ed2091186d31b6..94ab105a852ddc12b0875be230624382afe632a8 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -680,10 +680,16 @@ IPC_MESSAGE_ROUTED2(ViewMsg_SetZoomLevelForLoadingURL,
 // Set the zoom level for a particular url, so all render views
 // displaying this url can update their zoom levels to match.
 // If scheme is empty, then only host is used for matching.
-IPC_MESSAGE_CONTROL3(ViewMsg_SetZoomLevelForCurrentURL,
+// Render views in the exception list do not have their levels changed.
+IPC_MESSAGE_CONTROL4(ViewMsg_SetZoomLevelForCurrentURL,
                      std::string /* scheme */,
                      std::string /* host */,
-                     double /* zoom_level */)
+                     double /* zoom_level */,
+                     std::set<int> /* exceptions */)

[Fady Samuel, 2014/06/09 15:43:21]

It seems kind of heavy weight to iterate through and carry an exception level
across processes with every zoom level change. I wonder if it would be more
efficient to store an exception bit in the renderer and update that bit through
another IPC.

[wjmaclean, 2014/06/09 17:23:29]

Personally, I would think that a single IPC would be more efficient, since the
majority of the cost would be in setting up the message, and doing the
transmission. That being said, I have never seen performance metrics for this
sort of thing, so I can't be sure.

In most cases I would expect the set to be small or even empty.

The cost of the iteration is immaterial, as iterating over the temporary zoom
levels list in HostZoomMap should be small, we'd still have to do the iteration
in RenderThreadImpl.

If we *did* go this route, then I would suggest staying with the IPC below, but
knowing that once this is called on a render view that it automatically puts
itself into "temporary" mode, and RenderThreadImpl checks the status of each
view before trying to call SetZoomLevel on it. There would need to be another
IPC to reset the view though.

+
+// Set the zoom level for a particular render view.
+IPC_MESSAGE_ROUTED1(ViewMsg_SetZoomLevelForView,

[Fady Samuel, 2014/06/09 15:43:21]

To the comment above, the first parameter sets the exception bit, and the second
sets the zoom level.

ViewMsg_SetTemporaryZoomLevel(bool /* enabled */,
                              double /* level */)

+                    double /* zoom_level */)
 
 // Change encoding of page in the renderer.
 IPC_MESSAGE_ROUTED1(ViewMsg_SetPageEncoding,