diff --git a/content/base/public/nsContentCreatorFunctions.h b/content/base/public/nsContentCreatorFunctions.h
index 967e4c6425b7..b9c05a864268 100644
--- a/content/base/public/nsContentCreatorFunctions.h
+++ b/content/base/public/nsContentCreatorFunctions.h
@@ -6,7 +6,7 @@
 #ifndef nsContentCreatorFunctions_h__
 #define nsContentCreatorFunctions_h__
 
-#include "nscore.h"
+#include "nsError.h"
 #include "nsCOMPtr.h"
 #include "mozilla/dom/FromParser.h"
 
diff --git a/content/base/public/nsContentPolicyUtils.h b/content/base/public/nsContentPolicyUtils.h
index a68b6c9f979b..695932eab72b 100644
--- a/content/base/public/nsContentPolicyUtils.h
+++ b/content/base/public/nsContentPolicyUtils.h
@@ -15,17 +15,17 @@
 #define __nsContentPolicyUtils_h__
 
 #include "nsIContentPolicy.h"
-#include "nsIServiceManager.h"
 #include "nsIContent.h"
 #include "nsIScriptSecurityManager.h"
-#include "nsIPrincipal.h"
 #include "nsIURI.h"
+#include "nsServiceManagerUtils.h"
 
 //XXXtw sadly, this makes consumers of nsContentPolicyUtils depend on widget
 #include "nsIDocument.h"
 #include "nsPIDOMWindow.h"
 
 class nsACString;
+class nsIPrincipal;
 
 #define NS_CONTENTPOLICY_CONTRACTID   "@mozilla.org/layout/content-policy;1"
 #define NS_CONTENTPOLICY_CATEGORY "content-policy"
diff --git a/content/base/public/nsContentUtils.h b/content/base/public/nsContentUtils.h
index ceeceac0ffc6..038fd0e3f5e8 100644
--- a/content/base/public/nsContentUtils.h
+++ b/content/base/public/nsContentUtils.h
@@ -9,7 +9,6 @@
 #ifndef nsContentUtils_h___
 #define nsContentUtils_h___
 
-#include <math.h>
 #if defined(XP_WIN) || defined(XP_OS2)
 #include <float.h>
 #endif
@@ -21,7 +20,6 @@
 #include "js/TypeDecls.h"
 #include "js/Value.h"
 #include "js/RootingAPI.h"
-#include "mozilla/Assertions.h"
 #include "mozilla/EventForwards.h"
 #include "mozilla/GuardObjects.h"
 #include "mozilla/TimeStamp.h"
diff --git a/content/base/public/nsINameSpaceManager.h b/content/base/public/nsINameSpaceManager.h
index 90bd89c6c037..ba45dbf88174 100644
--- a/content/base/public/nsINameSpaceManager.h
+++ b/content/base/public/nsINameSpaceManager.h
@@ -7,10 +7,9 @@
 #define nsINameSpaceManager_h___
 
 #include "nsISupports.h"
-#include "nsStringGlue.h"
 
 class nsIAtom;
-class nsString;
+class nsAString;
 
 #define kNameSpaceID_Unknown -1
 // 0 is special at C++, so use a static const int32_t for
diff --git a/content/base/public/nsViewportInfo.h b/content/base/public/nsViewportInfo.h
index e039ba028792..bc02eff58bfa 100644
--- a/content/base/public/nsViewportInfo.h
+++ b/content/base/public/nsViewportInfo.h
@@ -6,7 +6,7 @@
 #define nsViewportInfo_h___
 
 #include <stdint.h>
-#include "nscore.h"
+#include "mozilla/Attributes.h"
 #include "Units.h"
 
 /**
diff --git a/content/canvas/src/WebGLContext.h b/content/canvas/src/WebGLContext.h
index 0804031c0a6e..7b3d203522d7 100644
--- a/content/canvas/src/WebGLContext.h
+++ b/content/canvas/src/WebGLContext.h
@@ -20,6 +20,7 @@
 #include "mozilla/dom/HTMLCanvasElement.h"
 #include "nsWrapperCache.h"
 #include "nsIObserver.h"
+#include "nsLayoutUtils.h"
 
 #include "GLContextProvider.h"
 #include "gfxImageSurface.h"
diff --git a/content/html/content/public/HTMLAudioElement.h b/content/html/content/public/HTMLAudioElement.h
index 32b6b6f15baf..746b083a5326 100644
--- a/content/html/content/public/HTMLAudioElement.h
+++ b/content/html/content/public/HTMLAudioElement.h
@@ -7,11 +7,12 @@
 #define mozilla_dom_HTMLAudioElement_h
 
 #include "mozilla/Attributes.h"
-#include "nsITimer.h"
 #include "nsIDOMHTMLAudioElement.h"
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/dom/TypedArray.h"
 
+class nsITimer;
+
 typedef uint16_t nsMediaNetworkState;
 typedef uint16_t nsMediaReadyState;
 
diff --git a/content/html/content/public/HTMLCanvasElement.h b/content/html/content/public/HTMLCanvasElement.h
index 4ae642b4143d..d5e32f51d5cf 100644
--- a/content/html/content/public/HTMLCanvasElement.h
+++ b/content/html/content/public/HTMLCanvasElement.h
@@ -12,10 +12,8 @@
 #include "nsGkAtoms.h"
 #include "nsSize.h"
 #include "nsError.h"
-#include "nsNodeInfoManager.h"
 
 #include "nsICanvasElementExternal.h"
-#include "nsLayoutUtils.h"
 #include "mozilla/gfx/Rect.h"
 
 class nsICanvasRenderingContextInternal;
diff --git a/content/html/content/public/HTMLMediaElement.h b/content/html/content/public/HTMLMediaElement.h
index e2281c83d9e1..0ce705d95434 100644
--- a/content/html/content/public/HTMLMediaElement.h
+++ b/content/html/content/public/HTMLMediaElement.h
@@ -9,37 +9,36 @@
 #include "nsIDOMHTMLMediaElement.h"
 #include "nsGenericHTMLElement.h"
 #include "MediaDecoderOwner.h"
-#include "nsIChannel.h"
-#include "nsIHttpChannel.h"
-#include "nsIDOMRange.h"
 #include "nsCycleCollectionParticipant.h"
-#include "nsILoadGroup.h"
 #include "nsIObserver.h"
-#include "AudioStream.h"
-#include "VideoFrameContainer.h"
 #include "mozilla/CORSMode.h"
 #include "DOMMediaStream.h"
-#include "mozilla/Mutex.h"
-#include "mozilla/dom/TimeRanges.h"
-#include "nsIDOMWakeLock.h"
 #include "AudioChannelCommon.h"
 #include "DecoderTraits.h"
-#include "MediaMetadataManager.h"
-#include "AudioChannelAgent.h"
+#include "nsIAudioChannelAgent.h"
 #include "mozilla/Attributes.h"
-#include "mozilla/dom/TextTrack.h"
 #include "mozilla/dom/TextTrackList.h"
-#include "mozilla/ErrorResult.h"
 
 // Define to output information on decoding and painting framerate
 /* #define DEBUG_FRAME_RATE 1 */
 
+class nsIChannel;
+class nsIHttpChannel;
+class nsILoadGroup;
+
 typedef uint16_t nsMediaNetworkState;
 typedef uint16_t nsMediaReadyState;
 
 namespace mozilla {
+class AudioStream;
+class ErrorResult;
 class MediaResource;
 class MediaDecoder;
+class VideoFrameContainer;
+namespace dom {
+class TextTrack;
+class TimeRanges;
+}
 }
 
 class nsITimer;
diff --git a/content/html/content/public/HTMLVideoElement.h b/content/html/content/public/HTMLVideoElement.h
index 921ce609ffa9..e0ae9ab19ca2 100644
--- a/content/html/content/public/HTMLVideoElement.h
+++ b/content/html/content/public/HTMLVideoElement.h
@@ -10,12 +10,12 @@
 #include "mozilla/Attributes.h"
 #include "nsIDOMHTMLVideoElement.h"
 #include "mozilla/dom/HTMLMediaElement.h"
-#include "mozilla/dom/VideoPlaybackQuality.h"
-#include "nsPerformance.h"
 
 namespace mozilla {
 namespace dom {
 
+class VideoPlaybackQuality;
+
 class HTMLVideoElement MOZ_FINAL : public HTMLMediaElement,
                                    public nsIDOMHTMLVideoElement
 {
diff --git a/content/html/content/public/nsFormSubmission.h b/content/html/content/public/nsFormSubmission.h
index c2bb97d3d60c..27802f0fb946 100644
--- a/content/html/content/public/nsFormSubmission.h
+++ b/content/html/content/public/nsFormSubmission.h
@@ -6,7 +6,6 @@
 #define nsIFormSubmission_h___
 
 #include "mozilla/Attributes.h"
-#include "nsISupports.h"
 #include "nsString.h"
 #include "nsCOMPtr.h"
 
diff --git a/content/html/content/public/nsIFormProcessor.h b/content/html/content/public/nsIFormProcessor.h
index af2b3b3657c8..72dc1c182c03 100644
--- a/content/html/content/public/nsIFormProcessor.h
+++ b/content/html/content/public/nsIFormProcessor.h
@@ -14,10 +14,10 @@
 #define nsIFormProcessor_h__
 
 #include "nsISupports.h"
-#include "nsIDOMHTMLInputElement.h"
-#include "nsTArray.h"
+#include "nsTArrayForwardDeclare.h"
 
 class nsString;
+class nsIDOMHTMLElement;
 
 // {0ae53c0f-8ea2-4916-bedc-717443c3e185}
 #define NS_FORMPROCESSOR_CID \
diff --git a/content/html/content/src/HTMLAudioElement.cpp b/content/html/content/src/HTMLAudioElement.cpp
index ad43500a8ce4..96ef7c683190 100644
--- a/content/html/content/src/HTMLAudioElement.cpp
+++ b/content/html/content/src/HTMLAudioElement.cpp
@@ -19,6 +19,9 @@
 #include <algorithm>
 #include "mozilla/Preferences.h"
 #include "nsComponentManagerUtils.h"
+#include "nsIHttpChannel.h"
+#include "mozilla/dom/TimeRanges.h"
+#include "AudioStream.h"
 
 static bool
 IsAudioAPIEnabled()
diff --git a/content/html/content/src/HTMLMediaElement.cpp b/content/html/content/src/HTMLMediaElement.cpp
index f79d5131aa4f..6aa73df091bf 100644
--- a/content/html/content/src/HTMLMediaElement.cpp
+++ b/content/html/content/src/HTMLMediaElement.cpp
@@ -75,6 +75,7 @@
 
 #include "nsCSSParser.h"
 #include "nsIMediaList.h"
+#include "nsIDOMWakeLock.h"
 
 #include "ImageContainer.h"
 #include "nsIPowerManagerService.h"
diff --git a/content/html/content/src/HTMLVideoElement.cpp b/content/html/content/src/HTMLVideoElement.cpp
index f12828de09b0..bbc2bee036d1 100644
--- a/content/html/content/src/HTMLVideoElement.cpp
+++ b/content/html/content/src/HTMLVideoElement.cpp
@@ -34,6 +34,9 @@
 #include "MediaError.h"
 #include "MediaDecoder.h"
 #include "mozilla/Preferences.h"
+#include "nsIDOMWakeLock.h"
+#include "nsPerformance.h"
+#include "mozilla/dom/VideoPlaybackQuality.h"
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Video)
 
diff --git a/layout/xul/tree/nsTreeColumns.h b/layout/xul/tree/nsTreeColumns.h
index 88f5a6cc9b85..e3176ecb55a8 100644
--- a/layout/xul/tree/nsTreeColumns.h
+++ b/layout/xul/tree/nsTreeColumns.h
@@ -13,6 +13,7 @@
 #include "nsCycleCollectionParticipant.h"
 #include "nsAutoPtr.h"
 #include "nsWrapperCache.h"
+#include "nsString.h"
 
 class nsTreeBodyFrame;
 class nsTreeColumns;