Fix errors in third_party/blink/common/BUILD.gn

Fix a few errors found with gn check.

gn check related output:
The target:
  //third_party/blink/common:common
has a source file:
  //third_party/blink/common/loader/throttling_url_loader.h
which was not found.
ERROR at //third_party/blink/common/mediastream/media_devices.cc:6:11: Can't include this header from here.
#include "media/capture/video/video_capture_device_descriptor.h"
          ^----------------------------------------------------
The target:
  //third_party/blink/common:common
is including a file from the target:
  //media/capture:capture_base
ERROR at //third_party/blink/common/mediastream/media_stream_mojom_traits.cc:9:11: Can't include this header from here.
#include "media/capture/mojom/video_capture_types_mojom_traits.h"
          ^-----------------------------------------------------
The target:
  //third_party/blink/common:common
is including a file from the target:
  //media/capture/mojom:video_capture_mojom_support

Change-Id: I86fffcdb242211e674d72a41e37d85405ddbb8f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2140431Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Chris Sharp <csharp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757183}

third_party/blink/common/BUILD.gn

@@ -80,7 +80,6 @@ jumbo_source_set("common") {
     "loader/mime_sniffing_url_loader.cc",
     "loader/resource_type_util.cc",
     "loader/throttling_url_loader.cc",
-    "loader/throttling_url_loader.h",
     "loader/url_loader_factory_bundle.cc",
     "loader/url_loader_factory_bundle_mojom_traits.cc",
     "loader/url_loader_throttle.cc",
@@ -132,6 +131,8 @@ jumbo_source_set("common") {
 
   deps = [
     "//base",
+    "//media/capture:capture_base",
+    "//media/capture/mojom:video_capture_mojom_support",
     "//mojo/public/cpp/system",
     "//net",
     "//services/metrics/public/cpp:metrics_cpp",