Create a ChromeBrowserHostImpl for every Chrome tab (see issue #2969)

The Browser object represents the top-level Chrome browser window. One or more
tabs (WebContents) are then owned by the Browser object via TabStripModel. A
new Browser object can be created programmatically using "new Browser" or
Browser::Create, or as a result of user action such as dragging a tab out of an
existing window. New or existing tabs can also be added to an already existing
Browser object.

The Browser object acts as the WebContentsDelegate for all attached tabs. CEF
integration requires WebContentsDelegate callbacks and notification of tab
attach/detach. To support this integration we add a cef::BrowserDelegate
(ChromeBrowserDelegate) member that is created in the Browser constructor and
receives delegation for the Browser callbacks. ChromeBrowserDelegate creates a
new ChromeBrowserHostImpl when a tab is added to a Browser for the first time,
and that ChromeBrowserHostImpl continues to exist until the tab's WebContents
is destroyed. The associated WebContents object does not change, but the
Browser object will change when the tab is dragged between windows.

CEF callback logic is shared between the chrome and alloy runtimes where
possible. This shared logic has been extracted from CefBrowserHostImpl to
create new CefBrowserHostBase and CefBrowserContentsDelegate classes. The
CefBrowserHostImpl class is now only used with the alloy runtime and will be
renamed to AlloyBrowserHostImpl in a future commit.

libcef/browser/browser_info.h

@@ -12,8 +12,10 @@
 #include "include/internal/cef_ptr.h"
 #include "libcef/common/values_impl.h"
 
+#include "base/callback.h"
 #include "base/containers/unique_ptr_adapters.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/values.h"
 
@@ -21,12 +23,12 @@ namespace content {
 class RenderFrameHost;
 }
 
-class CefBrowserHostImpl;
+class CefBrowserHostBase;
 class CefFrameHostImpl;
 
 // CefBrowserInfo is used to associate a browser ID and render view/process
-// IDs with a particular CefBrowserHostImpl. Render view/process IDs may change
-// during the lifetime of a single CefBrowserHostImpl.
+// IDs with a particular CefBrowserHostBase. Render view/process IDs may change
+// during the lifetime of a single CefBrowserHostBase.
 //
 // CefBrowserInfo objects are managed by CefBrowserInfoManager and should not be
 // created directly.
@@ -44,23 +46,24 @@ class CefBrowserInfo : public base::RefCountedThreadSafe<CefBrowserInfo> {
 
   // May return NULL if the browser has not yet been created or if the browser
   // has been destroyed.
-  CefRefPtr<CefBrowserHostImpl> browser() const;
+  CefRefPtr<CefBrowserHostBase> browser() const;
 
-  // Set or clear the browser. Called from the CefBrowserHostImpl constructor
+  // Set or clear the browser. Called from CefBrowserHostBase InitializeBrowser
   // (to set) and DestroyBrowser (to clear).
-  void SetBrowser(CefRefPtr<CefBrowserHostImpl> browser);
+  void SetBrowser(CefRefPtr<CefBrowserHostBase> browser);
 
   // Ensure that a frame record exists for |host|. Called for the main frame
   // when the RenderView is created, or for a sub-frame when the associated
   // RenderFrame is created in the renderer process.
-  // Called from CefBrowserHostImpl::RenderFrameCreated (is_guest_view = false)
-  // or CefMimeHandlerViewGuestDelegate::OnGuestAttached (is_guest_view = true).
+  // Called from CefBrowserContentsDelegate::RenderFrameCreated (is_guest_view =
+  // false) or CefMimeHandlerViewGuestDelegate::OnGuestAttached (is_guest_view =
+  // true).
   void MaybeCreateFrame(content::RenderFrameHost* host, bool is_guest_view);
 
   // Remove the frame record for |host|. Called for the main frame when the
   // RenderView is destroyed, or for a sub-frame when the associated RenderFrame
   // is destroyed in the renderer process.
-  // Called from CefBrowserHostImpl::FrameDeleted or
+  // Called from CefBrowserContentsDelegate::RenderFrameDeleted or
   // CefMimeHandlerViewGuestDelegate::OnGuestDetached.
   void RemoveFrame(content::RenderFrameHost* host);
 
@@ -121,6 +124,28 @@ class CefBrowserInfo : public base::RefCountedThreadSafe<CefBrowserInfo> {
   typedef std::set<CefRefPtr<CefFrameHostImpl>> FrameHostList;
   FrameHostList GetAllFrames() const;
 
+  class NavigationLock final : public base::RefCounted<NavigationLock> {
+   private:
+    friend class CefBrowserInfo;
+    friend class base::RefCounted<NavigationLock>;
+
+    NavigationLock();
+    ~NavigationLock();
+
+    base::OnceClosure pending_action_;
+    base::WeakPtrFactory<NavigationLock> weak_ptr_factory_;
+  };
+
+  // Block navigation actions on NavigationLock life span. Must be called on the
+  // UI thread.
+  scoped_refptr<NavigationLock> CreateNavigationLock();
+
+  // Returns true if navigation actions are currently blocked. If this method
+  // returns true the most recent |pending_action| will be executed on the UI
+  // thread once the navigation lock is released. Must be called on the UI
+  // thread.
+  bool IsNavigationLocked(base::OnceClosure pending_action);
+
  private:
   friend class base::RefCountedThreadSafe<CefBrowserInfo>;
 
@@ -151,11 +176,15 @@ class CefBrowserInfo : public base::RefCountedThreadSafe<CefBrowserInfo> {
   bool is_windowless_;
   CefRefPtr<CefDictionaryValue> extra_info_;
 
+  // Navigation will be blocked while |navigation_lock_| exists.
+  // Only accessed on the UI thread.
+  base::WeakPtr<NavigationLock> navigation_lock_;
+
   mutable base::Lock lock_;
 
   // The below members must be protected by |lock_|.
 
-  CefRefPtr<CefBrowserHostImpl> browser_;
+  CefRefPtr<CefBrowserHostBase> browser_;
 
   // Owner of FrameInfo structs.
   typedef std::set<std::unique_ptr<FrameInfo>, base::UniquePtrComparator>