Remove usage of FrameTreeNode IDs (see issue #2421)

With the introduction of prerendering in Chromium it is now possible for
RenderFrameHosts (RFH) to move between FrameTrees. As a consequence we can no
longer rely on FrameTreeNode IDs to uniquely identify a RFH over its lifespan.
We must now switch to using GlobalRenderFrameHostId (child_id, frame_routing_id)
instead for that purpose. Additionally, we simplify existing code by using the
GlobalRenderFrameHostId struct in all places that previously used a
(render_process_id, render_frame_id) pair, since these concepts are equivalent.

See https://crbug.com/1179502#c8 for additional background.

libcef/common/frame_util.h

@@ -8,14 +8,76 @@
 #include <stdint.h>
 #include <string>
 
+#include "base/logging.h"
+#include "content/public/browser/global_routing_id.h"
+#include "content/public/common/child_process_host.h"
+
+namespace content {
+class NavigationHandle;
+}
+
 namespace frame_util {
 
-// Returns the frame ID, which is a 64-bit combination of |render_process_id|
-// and |render_routing_id|.
-int64_t MakeFrameId(int32_t render_process_id, int32_t render_routing_id);
+// Create a frame ID in the format exposed by the CEF API.
+inline int64_t MakeFrameId(int child_id, int frame_routing_id) {
+  return (static_cast<uint64_t>(child_id) << 32) |
+         static_cast<uint64_t>(frame_routing_id);
+}
 
-// Returns a human-readable version of |frame_id|.
+// Create a frame ID in the format exposed by the CEF API.
+inline int64_t MakeFrameId(const content::GlobalRenderFrameHostId& global_id) {
+  return MakeFrameId(global_id.child_id, global_id.frame_routing_id);
+}
+
+// Returns true if |child_id| is valid.
+inline bool IsValidChildId(int child_id) {
+  // See comments in ChildProcessHostImpl::GenerateChildProcessUniqueId().
+  return child_id != content::ChildProcessHost::kInvalidUniqueID &&
+         child_id != 0;
+}
+
+// Returns true if |frame_routing_id| is valid.
+inline bool IsValidRoutingId(int frame_routing_id) {
+  return frame_routing_id != MSG_ROUTING_NONE;
+}
+
+// Returns true if |global_id| is valid.
+inline bool IsValidGlobalId(const content::GlobalRenderFrameHostId& global_id) {
+  return IsValidChildId(global_id.child_id) &&
+         IsValidRoutingId(global_id.frame_routing_id);
+}
+
+// Create a global ID from components.
+inline content::GlobalRenderFrameHostId MakeGlobalId(
+    int child_id,
+    int frame_routing_id,
+    bool allow_invalid_frame_id = false) {
+  DCHECK(IsValidChildId(child_id));
+  DCHECK(allow_invalid_frame_id || IsValidRoutingId(frame_routing_id));
+  return content::GlobalRenderFrameHostId(child_id, frame_routing_id);
+}
+
+// Create a global ID from a frame ID.
+inline content::GlobalRenderFrameHostId MakeGlobalId(int64_t frame_id) {
+  uint32_t child_id = frame_id >> 32;
+  uint32_t frame_routing_id = std::numeric_limits<uint32_t>::max() & frame_id;
+  return MakeGlobalId(child_id, frame_routing_id);
+}
+
+// Returns an invalid global ID value.
+inline content::GlobalRenderFrameHostId InvalidGlobalId() {
+  return content::GlobalRenderFrameHostId();
+}
+
+// Returns the best match of global ID for |navigation_handle|. For pre-commit
+// navigations this will return the current RFH, if any, or an invalid ID.
+content::GlobalRenderFrameHostId GetGlobalId(
+    content::NavigationHandle* navigation_handle);
+
+// Returns a human-readable version of the ID.
 std::string GetFrameDebugString(int64_t frame_id);
+std::string GetFrameDebugString(
+    const content::GlobalRenderFrameHostId& global_id);
 
 }  // namespace frame_util