Remove uses of base::hash_map from //chrome

chrome/browser/android/compositor/tab_content_manager.h

Index: chrome/browser/android/compositor/tab_content_manager.h
diff --git a/chrome/browser/android/compositor/tab_content_manager.h b/chrome/browser/android/compositor/tab_content_manager.h
index 331330b486c1e183db9306bd7be753dc4aa45d02..e5e7763ffbeec243364d267c38dd8105b20f06ef 100644
--- a/chrome/browser/android/compositor/tab_content_manager.h
+++ b/chrome/browser/android/compositor/tab_content_manager.h
@@ -7,11 +7,11 @@
 
 #include <jni.h>
 
-#include <unordered_map>
+#include <map>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_weak_ref.h"
-#include "base/containers/hash_tables.h"
+#include "base/containers/flat_map.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/layers/ui_resource_layer.h"
@@ -105,10 +105,12 @@ class TabContentManager : public ThumbnailCacheObserver {
 
  private:
   class TabReadbackRequest;
-  using LayerMap = base::hash_map<int, scoped_refptr<cc::Layer>>;
-  using ThumbnailLayerMap = base::hash_map<int, scoped_refptr<ThumbnailLayer>>;
+  // TODO(bug 714384) check sizes and consider using base::flat_map if these
+  // layer maps are small.
+  using LayerMap = std::map<int, scoped_refptr<cc::Layer>>;
+  using ThumbnailLayerMap = std::map<int, scoped_refptr<ThumbnailLayer>>;
   using TabReadbackRequestMap =
-      std::unordered_map<int, std::unique_ptr<TabReadbackRequest>>;
+      base::flat_map<int, std::unique_ptr<TabReadbackRequest>>;
 
   void PutThumbnailIntoCache(int tab_id,
                              float thumbnail_scale,