[Extensions] Remove old comment From XWalkExtensionProcessHost.
[Extensions] Use OnRenderProcessHostCreated to create a ExtensionProcessHost

This patch postpones the creation of a XWalkExtensionProcessHost until
a new RenderProcessHost is created. For achieving that we also had to
delay calling XWalkExtensionProcessHost::RegisterExternalExtensions.
[Extensions] Create Extensions' Infra per RenderProcess

For fully achieving it, this patch adds:
- One ExtensionProcess per RenderProcess;
- An InProcess ExtensionServer per RenderProcess;
- An InProcess MessageFilter per RenderProcess.

The patch also refactors XWalkExtensionService::OnRenderProcessHostCreated,
creating two helper functions to:
CreateExtensionProcessHost() and CreateInProcessExtensionServer().
[Extensions] Move ExtensionProcessHost, in_process server and message filter to a single struct

This patch adds a struct ExtensionData to XWalkExtensionService that will
be responsible for holding the data related to extensions per RenderProcess.

This has reduced our need of 3 maps to only one map.
[Extensions] Add test for 1-EP-per-RP
[Extensions] Make XW_Extension_EntryPoints.h consistent with other public headers
Merge pull request #968 from cmarcelo/public-header-consistent

[Extensions] Make XW_Extension_EntryPoints.h consistent with other publi...
Move resource_ids file outside runtime

The resource_ids file is an index for all the "grd" files that describe
resources (strings, images, data) we bundle with Crosswalk.

We want to provide resources for other parts of Crosswalk, so move this
index outside runtime/.
[Dialog] Use resource bundle instead of xwalk_js2c target

This patch changes our xwalk.experimental.dialog to use ResourceBundle
instead of our previous solution of generating a C source file to be
included.
[Extensions] Use ResourceBundle for storing JS instead of xwalk_js2c
[Runtime] Use ResourceBundle instead of xwalk_js2c.gypi
[Application] Use ResourceBundle instead of xwalk_js2c.gypi
[Extensions] Remove xwalk_js2c.gypi

This GYP file and the corresponding script are not used anymore. We now
bundle the JavaScript code using the resources system.
Merge pull request #960 from cmarcelo/resource-bundle

Use resources to bundle our JS files, drop xwalk_js2c solution
Merge pull request #939 from jeez/multi-eps

[Extensions] ExtensionProcess per RenderProcess implementation
[Extensions] Add tests for loading extension with multiple entry points

This test verifies that the extension is loaded even if the entry point
is in a different object than the one implicitly created by the extension
name.
[Extensions] Make entry points info available to the ModuleSystem

If we want to support loading extensions on demand, we have to make the
information for which entry points each extension will be accessible to
the entity responsible for loading extensions, in our case, the entity
is XWalkModuleSystem.
[Extensions] Add a way to tag extensions that will be loaded on demand

For now we will use a simple algorithm that will only load "leaf"
extensions on demand, for example, if "tizen", "tizen.time" and
"tizen.power" are in the extension list, we will enable loading on
demand for "tizen.time" and "tizen.power".
[Extensions] Load extensions on demand

Now that we have all the pieces it is time to put them together.

For each extension marked as 'should use the trampoline', we setup
"trap" acessors (for all entry points), that when run will load the
extension and create an instance for it. Before the extension is
loaded we need to remove all the references to the accessor function,
so it is not run anymore for those objects.