Add missing .h files to .gn files that have a .cc file next to it in the gn file already.

third_party/WebKit/Source/core/page/BUILD.gn

Index: third_party/WebKit/Source/core/page/BUILD.gn
diff --git a/third_party/WebKit/Source/core/page/BUILD.gn b/third_party/WebKit/Source/core/page/BUILD.gn
index d79c363f937384211edda66c55734582ae6e6ecf..0eff7b30a7a0e56ee523f3461e92829f262fc35f 100644
--- a/third_party/WebKit/Source/core/page/BUILD.gn
+++ b/third_party/WebKit/Source/core/page/BUILD.gn
@@ -11,18 +11,22 @@ blink_core_sources("page") {
     "ChromeClient.cpp",
     "ChromeClient.h",
     "ContextMenuController.cpp",
+    "ContextMenuController.h",
     "ContextMenuProvider.h",
     "CreateWindow.cpp",
     "CreateWindow.h",
     "CustomContextMenuProvider.cpp",
     "CustomContextMenuProvider.h",
     "DragController.cpp",
+    "DragController.h",
     "DragData.cpp",
     "EventWithHitTestResults.h",
     "FocusChangedObserver.cpp",
     "FocusChangedObserver.h",
     "FocusController.cpp",
+    "FocusController.h",
     "FrameTree.cpp",
+    "FrameTree.h",
     "Page.cpp",
     "Page.h",
     "PageAnimator.cpp",
@@ -41,9 +45,11 @@ blink_core_sources("page") {
     "PointerLockController.h",
     "PopupOpeningObserver.h",
     "PrintContext.cpp",
+    "PrintContext.h",
     "ScopedPageSuspender.cpp",
     "ScopedPageSuspender.h",
     "SpatialNavigation.cpp",
+    "SpatialNavigation.h",
     "TouchAdjustment.cpp",
     "TouchAdjustment.h",
     "TouchDisambiguation.cpp",